Strange coolant leak

[N Arizona]

I took my M1028 out on the road for the first time for some testing. When I got back to the house to check things over I noticed that there was coolant sprayed on the battery. I found some coolant by the Pass Alt as well. I looked for the leak but could not find one. I topped off the coolant let it cool down and ran it again but could not locate the leak. Has any one had this problem? I replaced the radiator hose and heater hoses when I got the truck. Here are some Pics.

 

[Barneyszoo]

Man hard to tell from the pix, I know when ever I top off the coolent on my truck it gose out the over flow untill it finds it own level. It never over heats so I guiss I'll just let it be an inch lower than the line. Might check the over flow drain see where it goes might be blowing back on the batterys

 

[FMJ]

I'm gonna say thermostat housing/tubing on the front of the engine in the area pictured in pic #3

 

[AZDeuce]

Well, well........I just had this happen to M1009 last night on the way home from work, red light came on, and I could see a little steam coming from the gaps on the hood, prior to that I thought I smelled anti-freeze.........yep I did. I was about a half a mile form a canal with water in it, so I decided to go that far (I was on country back farm roads). I pulled over popped the hood nothing but steam, and the top of the engine, batteries, and firewall were coated with anti freeze.

GREAT! Nothing good is going to come from this.

I couldn't find the leak source but was pretty sure it was up front, and naturally assumed the water pump. While I let her cool down I called my son on the cell phone, and asked him to rescue me, told him where I was, and to bring several gallons of water. About 20 minutes later he showed up with 4 gal of water and anti-freeze. Knowing I had a problem I just dumped the water in her. My son was watching the engine, and as soon as I started her he told me to shut her down, as I had a major leak.

He pointed out the area but it didn't make any sense, so I told him to start her and I'd watch. As soon as it started I saw a massive water leak, so I told him to shut her down. It didn't make any sense to me either, but I saw it with my own eyes. There is a hose about 1" or so, that goes from the oil filler pipe, to a EGR valve or some such contraption on the right side of the engine, it lays across a "crossover pipe" that goes across the intake manifold that carries cooland and on the left side I believe it houses the thermostat. where that hose lies over the crossover tube is where the leak is.

I lifted up the hose, and it had worn/rubbed a hole into the crossover pipe about 1/4" or so in diameter......WHAT IN THE WORLD!!??

Anyways, I know what I'll be doing this weekend! I gave my old take out 6.2 to a friend hopefully I can grab the crossover tube off of that. But the accesories on that engine are off a Hmmve, so I'm not sure if they use the same crossover tube...but I'll find out!

So my advise is to look under that hose, it may be wearing a hole in the crossover tube. While a PITA, it should be a relatively easy fix, as everything is on top of the engine. Now, I have to figure out how to keep the breather hose from doing that again.

 

[blzrgb]

Wow that's weird. Thanks for the info. I'll go check mine.

 

[3dubs]

I would say it has something to do with the new hoses and a loose nut. I just canged my hoses and found coolant leaking. I loosened the clamp and pushed the hose on all the way and clamped it again and the leak vanished. All joking aside first look to see if all the hoses on top are all the way on. Then look to see if any clamp is too far off. There is a ridge on all the fittings the hoses go on. Make sure the clamp is on past the ridge. If not a small amount of coolant will get by and it will be hard to find.

 

[StrykerPez]

Coolant leak? Psshhh... everybody knows that's normal!

Sorry, I have no experience on the CUCV, just the Deuce. Although in my civvy mechanical experience, I'd be leaning toward the hose too.

 

[N Arizona]

Thanks for all the responses. I check the hoses and every thing is tight and dry. I checked the crossover and thankfully everything is good. I fired up the truck and let it run for about a hour and no coolant leak. Very confusing. I did notice that the upper radiator hose never go pressure and going by the heat in Florida it should be open. I will change this out tomorrow and maybe this will fix it. The only other thing I can think of is a bad crossover gasket. It seems to do it when the motor is running at high RPMs. Keep the Ideas coming and thanks again.

 

[12vctd]

Could you possibly have a failing headgasket? I would look very closely at where the cyl head mates to the block.

 

[scottodog]

My m1008 just leaked in the same area but mine had three small pin holes on the bottom side of the heater core hose where the heater core flares out after the hose clamp.

 

[N Arizona]

I installed new heater hoses along with the radiator hoses. I have been dreading the idea that it might be the head gasket. I will do a new thermostat tomorrow and see if this fixes it. I read some of the other thread on the topic of coolant leaks and I will get a new radiator cap as well. Thanks again for the responses!

 

[12vctd]

Might wanna spend a few dollars and get a pressure tester for the cooling system, pressurize the entire system then you can check for leaks and see where they are coming from. This tool is priceless for diagnostic work. If the system wont hold pressure you should visually see the coolant leak or atleast a puddle. If theres no visual leaks on the outside, you might have to pull the oil pan and with someone pressurizing the system you can visually check each cylinder bore for coolant. I havent tried in a very long time but I am pretty sure you can rent a tester from autozone. Hopefully its just a a small problem.