Yet More coolant issues! 84' M923

[tbar123]

This coolant system is really starting to get on my last nerve. So far I have replaced the thermostat( tested before install and worked fine), coolant, filter, heater blower motor, rebuilt the actuator, flushed it, block heater twice,temp sensor twice and replaced upper rad hose twice. So I drove it into town today and guess what? Yep it overheated! Then the actuator didn't work, Of course. So I bolted the fan and that was of no help what soever. I was hoping to enter into the Memorial day parade, but now I'm really thinking of driving it off a cliff!!! When I got the truck home air was bleeding off out of the aluminum end on the actuator valve. What is causing that? My only other thought is to drain the fluid yet again, yank the thermostat and install a new water pump. Don't really want to do that! Any suggestions on what might be the problem? Oh, I did bleed air out of the system from the heater core relieve valve. IS there another place/better place to do this from? Thanks for any and all advice!

 

[Suprman]

Sounds like internal engine issues. If the heater blows out heat then coolant is circulating. You can have a good mechanic check the coolant for combustion mix.

 

[Csm Davis]

Tbar how do you know it is over heating? The sending units are known to read high when they fail.

 

[porkysplace]

Put a mechanical gauge on it see what the temperature really is , or get a infrared heat gun to check the temperature.

 

[doghead]

Is your shutterstat leaking air into the coolant?

 

[tbar123]

Thank you gents for the replies.
CSM Davis; I'm not exactly sure! I did replace the sending unit twice and it seems to be reading accurately. The main thing is massive amounts of air bleeding out of the actuator valve.Which leads me to the actuator valve receiving the excessive high temp, but not allowing the air to pass through the valve to actuate the fan.
Porkysplace; That's a good idea! I will have to say that those guns are not accurate at all. I deliver cold chain food. Everytime one of the stores I deliver to uses one of those guns(no matter how expensive or cheap ) they are they are always a minimum of 5 degrees off.
Doghead; I did check that and it seems that it is not, Would you know of a better way to test ? to make sure!
Gentlemen. I do thank all of you and I hope you all have a great weekend!

 

[63foxtrot]

sounds like bad head gasket, or block.

 

[tbar123]

63foxtrot; That is not what we are talking about!!!!! PLease God no bad engine or head gasket.............

 

[Suprman]

If you bolted the fan always on and it is in fact always spinning and you have proper coolant level with a clean flushed cooling system and have verified proper coolant flow there really isnt too much else that it can be. It is possible the fan shutter is leaking air into the cooling system and sort of air locking it. If the fan is bolted on, disconnect and plug the air feed to the fan shutter and see what happens.

 

[Csm Davis]

Okay Tbar slow your roll you have got to do this in order or by the book which is not a bad idea the TM'S will give you a step-by-step of how to trouble shoot this.

 

[tbar123]

When I was heading into town, I did pull into an Oreillys and pull the line from the fan clutch and no obstructions, That's when I bolted the fan. When I finally got home after my first post. I went out and tried to tighten the fan belt,The sprocket was so tight that it actually started to bend my prybar. I did loosen all 6 bolts . I'm hoping it's a water pump at this point. I did also check the new oil( less than 4 hours since change) and there is no sign of coolant in it.I also vented air from the system again, and it was a steady flow of coolant.

 

[WillWagner]

Do not remove the stat. Diesel is not like a car, two cooling loops. when the stat opens it closes off the block loop and opens the radiator/cooling loop. if the stat is not there the coolant will follow the path of least resistance, which is the block loop.

If when the engine is overheating, is it pushing coolant out of the overflow? Install a known good mechanical or digital temp gauge before you throw more parts at it.

 

[dawico]

If the thermostat is anything like the one in my 923a2 then it could be good and just sticking. Mine slides in a ring and a light sanding seemed to solve the problem.

Hope that helps and good luck.

 

[tbar123]

Alright, I ran some tests just now. I started the truck and 50 minutes later it reached a temp of 200. I let it go another 10 minutes for 1 full hour at idle and the temp was about 215. I then supplied air to the fan clutch and no drop in temp. I then purged some more air ,not really any came out. The drivers side of the radiator was cold and everything else was hot. The heater was blowing lukewarm water at best,but yesterday it was hot. I then shut the truck off reconnected the air lines to the actuator and it actually worked.But after 8 minutes of running no drop in temp. I'm thinking now that the stat is stuck like Dawico said, and/or the water pump is shot. Also There is nothing in the oil, and no smoke after start up. How stiff or how hard should it be to move the tensioner on the pump drive belt? I'm guessing it shouldn't bend a prybar tough!

 

[WillWagner]

A failed w/p will make the temp climb immediately, cold lower hose and a hot upper hose at the stat hsg and a cool radiator at the inlet...the temp will get cooler at the top hose the closer to the radiator. Sounds like a stuck open stat. There is a seal in the stat housing, you should do that too when you do the stat. You should still put a known good mechanical gauge in it. The w/p can be a biatch to move if it hasn't moved in a long time. If you do a stat, best advice is to take the w/p off and install a new seal ring. Clean the area on the pump and block with a hand held wire brush, not one on a drill, and when you reinstall the pump, never seize the crap out of the seal ring.

 

[tbar123]

I opened up the stat and removed it. I then retested it to make sure it opened and it did. I then brought the housing in and retested the stat and fitted into the housing to make sure it closed and it did. I then reinstalled it into the motor and restarted the motor and the temp went above the opening temp of the stat. At this point the fan clutch never stopped, continuous run. Like I said before I'm out of thoughts. I'm ready to sell.Anyone want to buy an extremely over priced broken down truck!!!!

 

[Bobertb]

could the radiator be plugged internally

 

[dawico]

could the radiator be plugged internally

Could test that by removing the hoses and flushing it.

 

[dawico]

I opened up the stat and removed it. I then retested it to make sure it opened and it did. I then brought the housing in and retested the stat and fitted into the housing to make sure it closed and it did. I then reinstalled it into the motor and restarted the motor and the temp went above the opening temp of the stat. At this point the fan clutch never stopped, continuous run. Like I said before I'm out of thoughts. I'm ready to sell.Anyone want to buy an extremely over priced broken down truck!!!!

Another thing I found while working on my truck (again, an a2 but may be similiar). The small hoses going to the reservoir were plugged. One comes from the top of the radiator. This one allows the air to escape the radiator and let the radiator fill completely.

I had many small issues to figure out to get my cooling system working properly. I checked everything, even the simple stuff, to get it all operating properly.

Good luck and keep up the fight.

 

[wheelspinner]

How stiff or how hard should it be to move the tensioner on the pump drive belt? I'm guessing it shouldn't bend a prybar tough!

tbar, did you READ the TM on belt tensioning for this engine? Using a pry bar, I have to imagine that you did not. There is a process, which is not intuitive to it. You MAY want to read up on it.