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Discussion Starter #1
I did some more checking on my coolant system this weekend...trying to find reasons why she's down every few months.

I checked the upper rad hose a few more times when cold...and it still takes a few minutes after the truck is running, before it gets hard. I also took a mirror and held it over the oil filler neck, and oil dipstick tube after shutting it off. There was no vapor from the dipstick tube, but I did have vapor from oil filler neck. That vapor DID NOT steam the mirror though.

Then I went around to the back of the truck, and held the mirror to the exhaust. When I did that, the mirror steamed a small amount. It wasn't enough to completely cloud up the mirror...not even close...but there was definitely a small amount of steam on it.

I'm about to spend money on mods for this truck...and I'd hate to do that when I have a problem that's developing, and will end up costing me more in the long run.

Any thoughts on the coolant issue?

Jamie
 

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I suspect you've got a head gasket going south.

I had a similar problem. Low coolant light every month or so. If you haven't got it already, you'll start to get white smoke upon startup in the morning or after it sits for some time.

Don't wait too long, as eventually, you may damage the cylinder head(s).

Since you're lining up lots of mod work, now is the time to strip down the heads and at least get them checked out (valves, guides)....

Good luck...
 

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JS, You could try this. I know it's a bit more of a job than you're looking for but, it may tell you what you want to know. I've used it successfully. It doesn't always work, depends on the conditions causing the leak.

Remove all the glow plugs, put a pressure tester on the radiator, pump up 15 lbs of pressure, let it sit and keep pumping the pressure up to 15 lbs. Keep it at 15 for 15-20 minutes. Then, unhook the power/fuse that powers the injector pump so you have no fuel flow to the injectors. Place sheets of cardboard along both sides of the engine, in front of the glow plug holes.

Have someone crank the engine over for a few seconds and check the cardboard for coolant. If you watch, you may see coolant coming out of one or more of the glow plug holes. If your leak is severe enough, this will usually work to help diagnose which side/cylinder is leaking. Hope it helps. Fred
 

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Discussion Starter #4
So it's the small amount of steam that was on the mirror, (at the exhaust), that is making it look like a head gasket leak? Crap. I was hoping things were okay, and my coolant loss was actually from some other source...like a leak at the coolant tank cap, or a fitting somewhere. Crap again.

Fred, that is more work than I think I'd tackle on my own, but I am going to make an appt with my mechanic this week so he can do some testing for me.

Triple crap.

Jamie
 

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So it's the small amount of steam that was on the mirror, (at the exhaust), that is making it look like a head gasket leak? Crap.
Jamie
Actually one of the two byproducts of combustion of a hydrocarbon fuel is water. (The other CO2, with trace CO emissions). So having water in teh exhaust is not abnormal.

The best test IMHO short of pulling the heads is to do a combustion gas coolant test. There are test strips that will detect combustion by-products in the coolant that get there from eitehr a head gasket leak, or a cracked head/block.
 

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Discussion Starter #6
NEHOG,

You just gave me a little glimmer of hope. I never even thought about the steam coming from water in the exhaust. And I probably should have said in my first post that I can't smell any coolant at the exhaust at all.

I won't get carried away though, and will still have my mechanic check things out for me this week.

Any other thoughts on this coolant mystery?

Jamie
 

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Actually one of the two byproducts of combustion of a hydrocarbon fuel is water. (The other CO2, with trace CO emissions). So having water in teh exhaust is not abnormal.
:exactly: this is why you see some cars spewing water out the tail pipe at, say a red light. catalytic convertors are designed to chemically alter the process of combustion gasses to water and water vapour.
 

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I would try some radiator stop leak. I use "BARS" stop leak. I usually put it in cold , top off the radiator with water and go on a fifteen to twenty minute drive to build pressure up. Let it sit overnite.

Pressure test system. Think NAPA sells some test strips to see if there is exhaust in the radiator. or something like that I guess.
 

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The test setups don't work well on a diesel. I know that mine is losing coolant from compression entering the cooling system, but yet I have tested it numerous times with those kits and it pass's every time. So the test aint that great. And I would use the GM tablets to slow the leak not BARS. The GM tablets are organic and won't cause disimilar metal problems.
 

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GM "horse Pills" work too. Used them on my caddy like gm said. Never had a problem with water leaks.
 

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oh heck y'all go to walgreens and order some water glass think back few years has always worked for me when i needed it to many moons ago had a olds that would empty the rad within 10 mins poured 2 pts into rad and many years later never lost a drop water glass is main compnent in stopleak only get at a drug store tho if you can find in pure form
 

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Discussion Starter #12
Thanks for all the info guys...I appreciate everyone chiming in like this. I have an appt for the truck on Friday, so I will post the findings when I hear back from the garage.

Jamie
 

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Ditto on the test strips. I also have the old style "Bloc-Check" that NAPA sells. It has never shown a color change when hooked up to a diesel. Gas engines, yes, right away. Needs the CO and HC to work.

I've tried it on Olds 5.7's that you couldn't keep the coolant in the system because of the combustion pressure and they still would not turn the blue liquid to green or yellow like they're supposed to.
 

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Liquid Glass that I used breaks down in anti freeze. We use only in our racecar with no anti-freeze.
 
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