Received 2002 M1097A2 for firetruck build - looking for advice

[draymorris]

So yall are saying it will have run flat inserts for sure? I will check into Feltz.

I found all the fluid call outs - so that is what I will go with. Sounds to me like Dexron 3 is what everyone is staying with.

The current top is soft top. The door windows are bad - Green top with Red paint will look .... So, we are exploring our options.

The current issue is the engine is overheating. I have checked the gauge and sender that is all good. The thermostat opens as it should in my pot on the stove. Engine temp climbs steady upon start up and keeps going. I have compared gauge with thermal camera and I believe the guage is reading right. All other things check out - belt, fan, etc - I hope we don't have a head problem - I will be looking closer into that tomorrow afternoon hopefully. I have not noticed anything that just slaps me in the face - like steam in the tailpipe or anything. Maybe the thermostat was stuck and I freed it up in the pot - will have to put it back together tomorrow and test run.

 

[Mogman]

So yall are saying it will have run flat inserts for sure? I will check into Feltz.

I found all the fluid call outs - so that is what I will go with. Sounds to me like Dexron 3 is what everyone is staying with.

The current top is soft top. The door windows are bad - Green top with Red paint will look .... So, we are exploring our options.

The current issue is the engine is overheating. I have checked the gauge and sender that is all good. The thermostat opens as it should in my pot on the stove. Engine temp climbs steady upon start up and keeps going. I have compared gauge with thermal camera and I believe the guage is reading right. All other things check out - belt, fan, etc - I hope we don't have a head problem - I will be looking closer into that tomorrow afternoon hopefully. I have not noticed anything that just slaps me in the face - like steam in the tailpipe or anything. Maybe the thermostat was stuck and I freed it up in the pot - will have to put it back together tomorrow and test run.

Is the fan coming on? at speed you would know, they make allot of noise, to test you can unplug the TDM module and the fan will run all the time so you could test if that helps.

 

[rhino1515]

So yall are saying it will have run flat inserts for sure? I will check into Feltz.

A few ways to find out. You can let the air out of a tire and see how it settles - or - you can weigh a wheel. If I remember correctly, a wheel with the large one-piece rubber runflat will be about 160 pounds, without just over 100 pounds - give or take. I'm sure someone will correct me if I am off base on those weights.

I found all the fluid call outs - so that is what I will go with. Sounds to me like Dexron 3 is what everyone is staying with..

You may also want to consider replacing the glow plugs right off the bat. They are fairly cheap and will give you some insight on how the engine has been running. Just make sure you get quality ones.

The current top is soft top. The door windows are bad - Green top with Red paint will look .... So, we are exploring our options..

Well, if it were me in that vehicle, and the poo hit the fan and we were going to get burned over, I would probably want hard doors/roof...

The current issue is the engine is overheating. I have checked the gauge and sender that is all good. The thermostat opens as it should in my pot on the stove. Engine temp climbs steady upon start up and keeps going. I have compared gauge with thermal camera and I believe the guage is reading right. All other things check out - belt, fan, etc - I hope we don't have a head problem - I will be looking closer into that tomorrow afternoon hopefully. I have not noticed anything that just slaps me in the face - like steam in the tailpipe or anything. Maybe the thermostat was stuck and I freed it up in the pot - will have to put it back together tomorrow and test run.

Good luck trying to hunt down the problem - could be a bunch of things. I typically do a full coolant system flush and replace all of the hoses and belts on every HMMWV that comes through my shop from the Government. Cheap insurance, I figure.

 

[draymorris]

I saw that fan override in the book. So I will try that tomorrow.

Something else I notice while test the temp gauge - there is a pulsing on the electrical system after a bit, as if the glow plugs are being on for a second off for a second. It will eventually stop, but it even did it when the engine was showing 145 degrees.

 

[Mogman]

I saw that fan override in the book. So I will try that tomorrow.

Something else I notice while test the temp gauge - there is a pulsing on the electrical system after a bit, as if the glow plugs are being on for a second off for a second. It will eventually stop, but it even did it when the engine was showing 145 degrees.

That is called afterglow it should stop 2-3min after startup, you can generally see it on the volt meter, the needle will swing back and forth, that is a good thing, means your PCB is working.
It would not be uncommon to see 230deg on a HMMWV the gauges are also not known for their accuracy, double check with a laser temp gauge at the thermostat housing

 

[mgFray]

For the fan, my recommendations..

With the engine off, can you spin the fan blades? If you can, the clutch might not be any good.

When the engine running, unplug the power lead to the cadillac valve (by the washer tank on the drivers side cowl under the hood). If the clutch is working well, the engine will lug down and the fan will spin will full engine force/rpm.. (otherwise it just "spins", but with very little force)

If all of that passes, then look at the radiator top down, see if it's clogged. Mine had a ton of pine needles and other debris between the seconds and very little airflow. Once I cleaned it out, it cools great.

The way the cooling works is engine spikes to 230F (or so), clutch kicks in and then it cools to a bit over 205F (or so).. and cycles that way. So as long as you are staying under 230F, then it's "fine".. go much above that and you can fry the head gasket and other issues.

(if you are concerned about overheating issues, definitely check the radiator tank for combustion. Mine seemed to be working great, but it was slowly leaking combustion into the coolant, until one day the slow leak was bad enough it puked all of the coolant out and really caused problems!)


As for tops, there are a few people who make custom tops. If soft top is "ok" for you, look up "blue ox tops", William Welch. (This is a facebook group!) He makes custom soft-tops and doors. May be worth your time to see if he would do red or another suitable color. (If you want hard top then you'll need to search elsewhere.)


Finally the glow plugs, if they are at all questionable (unknown), I would pull one. If it's at all warped on the end, replace the group of them. Don't buy replacement parts of ebay, go to MacMotors or Kascar (real4wd). They're about $8, but you WANT authentic ones! (Also the HMMWV should start within a 1-2 seconds of going from run to start. If it doesn't, you glow plugs or glow plug system may have an issue. When I started, people told me 5, 10 even 20 seconds of cranking was normal -- it's NOT.)

 

[TOBASH]

So yall are saying it will have run flat inserts for sure? I will check into Feltz.

I found all the fluid call outs - so that is what I will go with. Sounds to me like Dexron 3 is what everyone is staying with.

The current top is soft top. The door windows are bad - Green top with Red paint will look .... So, we are exploring our options.

The current issue is the engine is overheating. I have checked the gauge and sender that is all good. The thermostat opens as it should in my pot on the stove. Engine temp climbs steady upon start up and keeps going. I have compared gauge with thermal camera and I believe the guage is reading right. All other things check out - belt, fan, etc - I hope we don't have a head problem - I will be looking closer into that tomorrow afternoon hopefully. I have not noticed anything that just slaps me in the face - like steam in the tailpipe or anything. Maybe the thermostat was stuck and I freed it up in the pot - will have to put it back together tomorrow and test run.

This is an old truck with an old stack. Try cleaning the stack and try cleaning / boiling the radiator. Dirt gets in there and blocks air flow. Ask me how I know… I always turned her off before she hit 210.

Laser check the radiator to see if hot water is getting to it. You can pull out the thermostat and safely run without it temporarily.

My cure was replace all the stack components. New radiator, tranny cooler, power steering cooler. (My parts were all leaking so it was a no brainer. )

 

[draymorris]

This is what I did today. Put a new t stat in just for fun, since I ordered it yesterday from a local store and I like paying for what I order when possible, instead of sending it back even though the old t stat tested good last night. Sure enough no change. I had gone through the steps in the book to test the gauge - but I should have known that those procedures are not enough. So I disconnected the air purge line from the top of the t stat housing at the coolant reservoir - flows like it should. Then I let the hose run into the top of the reservoir and put a thermometer in the flow coming out of the hose - it was cold - about 170 yet the temp gauge was pegged high. So I let it run - the coolant temp got up to about 200 then dropped to 191 then stayed in that range - this tells me the t stat is working. Temp gauge stayed pegged the whole time. If the block can get that hot where the sending unit it mounted - compared to the t stat coolant temp. Then I have a problem in the block. There is not signs of head issueds - bubbling, pressure, smell at the exhuast ect. So I am going with bad sending unit or guage - unless someone has a better theory.

Fan works as is should - won't turn by hand, and engages when I unplug that wire. I could see no debris at all in the stack - this whole unit is clean as a whistle, has some tree moss growing on it on one side. The whole thing looks barely used. It has marks on it like it was just serviced based on the odometer.

I think we need a hard top - I think soft tops are asking for melted plastic with embers flying around. We are going to build a cage on the back where 2 can stand up and spray water. That is the way we do it around here - we rarely drag hose from the reel. If it gets in the brush it is usually something we can not walk through, so staying in the truck is best. We use pumps that can do 200 psi plus so we will turn the pressure up to try to reach out, but after that we wait for the air support. Having said that, we may make a top that works with our hand rail system. There are some local machine shops with rollers that we will talk to that can probably make a rounded smooth top that might look good. But I will chech out those people mentioned above.

Our 2.5 ton is a Blue Ox, so I guess the chief is familiar with them.

What would be the best guage fix - keep the military gauge and sender - go with something else and try to find 24 volt parts - or go with easy to find automotive and run some 12v wires?

I got into a deal with a generator controller retrofit one time where the sending unit would not work correctly with the controller. By the time I got it corrected I had learned way too much about different sending units. Bottom line, not only is the resistance important, so is the curve related to the temperature, of that resistance - not to mention some are low to high and some are high to low. So I am guessing the military did not want to have the guys testing the sender on the bench so they left out that diagnostics.

On that generator, I gave up on finding a sender that would work with the built in curves on the controller. So I brought a sender home, taped a digital thermometer to it and a meter for resistance - started in the freezer and let it warm up, then put it in boiling water and took notes the whole time and built my own curve. The controller allowed for me to install that curve and now that 600 Kw genset uses a late 70 s ford sending unit. And it reads correctly.

Keep the suggestions coming. Thanks to all

 

[Mogman]

No reason the re-invent the wheel, only two components to deal with and the next guy will appreciate it being stock, at least I would, does it start out indicating cold and then go to maxed out?
Are all the other gauges acting normally?
I think CAMO has measured the curve on that sending unit not sure but maybe he will chime in.

 

[mgFray]

After dealing with a bad oil pressure sensor, I just replace the gauge and sensor as a unit now (unless I know for sure it's the gauge). The minimal cost saves on the headaches and labor. (On my bad pressure sensor, I throught it was a bad gauge, replaced the gauge, replacement worked for one trip, then the gauge failed EXACTLY the same as the previous.. replaced the sender AND the gauge, no problems. I'm guessing there was some sort of a fault in the sender that was frying the gauge...)

 

[draymorris]

No reason the re-invent the wheel, only two components to deal with and the next guy will appreciate it being stock, at least I would, does it start out indicating cold and then go to maxed out?
Are all the other gauges acting normally?
I think CAMO has measured the curve on that sending unit not sure but maybe he will chime in.

Yes it seems to start out ok, That is what threw me off- yesterday I started it and watched it climb. Got my thermal camera out and the upper radiator hose was the same temp as the gauge was reading , about 145, so I was content that it was reading right. That is when I pulled the t stat. I did not test it until after I ordered a new one - so I got on here last night and after the test. Today after replacing the t stat - it climbed the same and I checked all the other items.

Maybe to further clarify - it keeps climbing until it is pegged. I did not let it do that yesterday because I want to pull the t stat and on a cooler engine. So today was when I let it peg and measured the coolant with a digital thermometer.

Just in case - is there any history of these engines having a flow problem down there where the sender is located.

I agree with keeping it stock if the new parts are good - I just don't want to replace a problem with the same problem - like I said, this thing looks like it was used to go to the grocery store. Why would the temp sender go out?

 

[juanprado]

Project 56 Manual for future reference in case link gets taken down

 

[draymorris]

Project 56 Manual for future reference in case link gets taken down

I downloaded it and save it and presented to the "chief". I really liked it, has good loading information. I think they were a little too worried about the loading. I wonder how they vent their tank to be able to go up and down 60 degrees without puking all the water out. I know there are devices that should close when water hit them, but I don't think that is the way to go. We would blow the tank when filling if we used such devices. So to think about going up a steep mountain that needs the loading to be perfect, just does not seem in the cards. But like I said - I got a lot out of it, and I am glad they published it.

Thanks again

 

[Mogman]

Yes it seems to start out ok, That is what threw me off- yesterday I started it and watched it climb. Got my thermal camera out and the upper radiator hose was the same temp as the gauge was reading , about 145, so I was content that it was reading right. That is when I pulled the t stat. I did not test it until after I ordered a new one - so I got on here last night and after the test. Today after replacing the t stat - it climbed the same and I checked all the other items.

Maybe to further clarify - it keeps climbing until it is pegged. I did not let it do that yesterday because I want to pull the t stat and on a cooler engine. So today was when I let it peg and measured the coolant with a digital thermometer.

Just in case - is there any history of these engines having a flow problem down there where the sender is located.

I agree with keeping it stock if the new parts are good - I just don't want to replace a problem with the same problem - like I said, this thing looks like it was used to go to the grocery store. Why would the temp sender go out?

It's over 20 years old, stuff breaks, I would suspect the gauge but I certainly could be wrong. The temp sensor, an RTD ( resistance temperature detector) is a pretty simple device.

 

[Milcommoguy]

MOGMAN
I think CAMO has measured the curve on that sending unit not sure but maybe he will chime in.
[/QUOTE]

I do have a question ?? Has the systems been flushed really good. I have seen rusted up systems with more crud, less coolant, lol

I have a minute and searched past posts. Let your fingers to the searching...... Here goes>>>>>

CAMO on the hi dive into hot water... The temperature guage to test tracking works out to...

OPEN circuit = no reading
Short circuit = full scale
120 degrees =2250 ohms
160 " = 1700 ohms
200 " = 890 ohms
240 " = 640 ohms

This data is useful to check the guage in place with sender removed. I have found the wonky reads are to mechanical failures due to water intrusion. (rusted, busted, gummed up or just plain worn out. Good batch of gauges average +/- a needle width with the test above..

NOW it is important that grounds and don't get all crazy on me with grounding stories... BUT the little horse shoe brackets and loose nuts (that funny) to make the ground to the meter stud are most problematic. Our fix is to " double nut the stud to the lug". Have seem many gauges held in and grounded with the same one nut. Over time bracket bend, never tight enough, plastic remolds, corrosion sets in... loss of connection and there goes any chance of a reliable reading. Outside temperature, moisture, time of day or just bang on it like a Las Vegas slot machine till it plays nice.

And to the electrical fan control... That thermostatic switch in the crossover is the heart of it all. YES, it work backwards conventional wiz-dum. Switch On is fan OFF and OFF (open circuit) is fan ON. Pulling any plug, system goes into fail safe and that's FAN ON.

Fan ON and... MY guess, it would be hard to get to 190 degrees unless pulling a heavy load. IMO... with everything else clean and pumping, at pressure, and correct water thermostat. Note those switches go bad in all ways possible. Buy quality "BLUE TAG" do not china out on this item.

When fan is engaged...It's a hurricane, CAMO at Camoteksystems.com


1986 M998 Helmet Top with many upgrades.
Built for Fun and Amateur Radio Comm's WA6VVC/ WA6CAM
Owner, Camoteksystems

 

[draymorris]

MOGMAN
I think CAMO has measured the curve on that sending unit not sure but maybe he will chime in.

I do have a question ?? Has the systems been flushed really good. I have seen rusted up systems with more crud, less coolant, lol

I have a minute and searched past posts. Let your fingers to the searching...... Here goes>>>>>

CAMO on the hi dive into hot water... The temperature guage to test tracking works out to...

OPEN circuit = no reading
Short circuit = full scale
120 degrees =2250 ohms
160 " = 1700 ohms
200 " = 890 ohms
240 " = 640 ohms

This data is useful to check the guage in place with sender removed. I have found the wonky reads are to mechanical failures due to water intrusion. (rusted, busted, gummed up or just plain worn out. Good batch of gauges average +/- a needle width with the test above..

NOW it is important that grounds and don't get all crazy on me with grounding stories... BUT the little horse shoe brackets and loose nuts (that funny) to make the ground to the meter stud are most problematic. Our fix is to " double nut the stud to the lug". Have seem many gauges held in and grounded with the same one nut. Over time bracket bend, never tight enough, plastic remolds, corrosion sets in... loss of connection and there goes any chance of a reliable reading. Outside temperature, moisture, time of day or just bang on it like a Las Vegas slot machine till it plays nice.

And to the electrical fan control... That thermostatic switch in the crossover is the heart of it all. YES, it work backwards conventional wiz-dum. Switch On is fan OFF and OFF (open circuit) is fan ON. Pulling any plug, system goes into fail safe and that's FAN ON.

Fan ON and... MY guess, it would be hard to get to 190 degrees unless pulling a heavy load. IMO... with everything else clean and pumping, at pressure, and correct water thermostat. Note those switches go bad in all ways possible. Buy quality "BLUE TAG" do not china out on this item.

When fan is engaged...It's a hurricane, CAMO at Camoteksystems.com


1986 M998 Helmet Top with many upgrades.
Built for Fun and Amateur Radio Comm's WA6VVC/ WA6CAM
Owner, Camoteksystems
[/QUOTE]
Thanks for the info. I was just thinking about ordering a new sender and getting the resistance figured out just to be able to test. But now I don't need to. Will check the grounding on the back of the gauge again, although I think I already did. I try to be good about that from the start but easy enough to do again. Makes sense about the gage bracket loosening and causing problems.

I probably should just order a new gauge and sender, but that approach always seems to bite me. So I will do some testing.

The fan works good. I really don't think that there is a radiator problem. Famous last words I know. But there was no sign of anything in the t stat housing, the fluid is clear and green, there are marker markings showing -40 at 4030 miles which is about what it has on it now, so it was being maintained (I would think).

I will keep you posted. Probably be a few days before I can get back to it though.

Is that sender a 3/8 pipe thread?

 

[williamh]

I’m having the same overheating issue. Fan works great but under load it heats up quickly , I replaced the t-stat first thinking it was the issue but it still gets hot. was gonna scope the top of radiator to see if it’s plugged when I replaced the upper hose but haven’t gotten around to it yet. I’ve been waisting time on gonna/shoulda done it projects lately. Summers a b***h lately in the working world. Gonna try and put a know good mechanical gauge on it to see what’s up. Temp gun on the bottom of the radiator looks good but out of the t-stat is high.

Just my 2c

 

[draymorris]

I’m having the same overheating issue. Fan works great but under load it heats up quickly , I replaced the t-stat first thinking it was the issue but it still gets hot. was gonna scope the top of radiator to see if it’s plugged when I replaced the upper hose but haven’t gotten around to it yet. I’ve been waisting time on gonna/shoulda done it projects lately. Summers a b***h lately in the working world. Gonna try and put a know good mechanical gauge on it to see what’s up. Temp gun on the bottom of the radiator looks good but out of the t-stat is high.

Just my 2c

My 2cent is about the same at this point - I am going to temporarily install a mechanical ga that I have in my junk (brand new) and see what it reads.

I don't want to sound like a know it all, ever - but.... I have a very expensive thermal imager made by Fluke - I don't use it all the time and it has been years since I studied how to use it correctly. But I can say this with certainty - measuring IR is not really just point and click - Aluminum, bare, is a IR mirror and will give me a bad temperature reading if I don't adjust the settings in the camera. And if I remember correctly, aluminum can ("can" being a key word here) throw the whole images temperatures off. So to rely on a temp reading from an IR device can be in error if aluminum is in the field of view that the device is capable of reading. Bottom line, don't trust the temp reading if you think something is wrong. So even with this $12K dollar camera, I won't trust the temp reading on the block unless I am sure there is nothing but steel or iron in the image. I don't want to take the time to learn how to adjust the camera at this point, so I am going to us a mechanical guage and get a reading at the coolant, not the surface of the metal. That is another thing I learned - surface temp can be way off- many factors involved in reading temperature.

I went through a lot of grief with some new generators that had a bad design flaw in their coolant systems that was causing the radiator to plug internally. It is a long story and I think I posted it here years ago. But it taught me a lot. Unfortunately, it made me look at these problems in a more complicated way, so here I am doing more diagnostics instead of throwing a $130 sender and guage on it.

But when I am done, I will have a temp gauge I will trust.

From what I have read - some of the dodge cummins had a engine block problem that created a hot spot, and the 6.0 fords had a hot spot in the heads or block that caused some major failures. Don't want to get into all the controversy around those two engines, but it makes me wonder here, if my coolant is 200 at the t stat, and the temp sender is correct, then I have a problem in a water jacket. Maybe someone put river water in it at one time an corroded things in the block - doubtful, but...

 

[rhino1515]

IMHO... spend the time/money to get that system flushed correctly before throwing a bunch of parts at it. It's something that should be really done regardless on an unknown history government vehicle. What you see come out will also give you a good idea of the history of that unit. If it turns out that it helps the problem, cool. If not, at least you know that was done and good to go.
If you haven't yet, a system pressure test may also tell you some things as well.

 

[TOBASH]

Clean the stack. Clean the inside of the radiator. Replace the hoses and ensure none of them were collapsing under vacuum effect.

Use a laser thermometer and stop wasting time assuming the gauges are buggered