Stumped about coolant loss.

[centrex]

I have done a search and I fear this may be another HG prob.

I had to fill my coolant overflow last week and it has just started idling slightly rough.

I replaced the plugs and they all looked identical. I took it to my local truck shop to have it pressure and compression tested. It came back with no compression problems and no leaks (except the radiator cap had a slight leak so new cap).

I took it on a round trip about 160kms today and it used just over an overflow tank of coolant.

I topped it up and let the engine cool and did a bubble test when it was cool. There was some dripping from the exhaust which soon disappeared when the engine warmed up. I also noticed there was some white goo (condensation??) in the engine oil cap so I thoroughly cleaned it but it has since returned.

Could the coolant be going straight into the exhaust somehow not affeccting compression??

Could the coolant be going in only when it is cold or when the engine is shut off??

What can I get my truck shop to test now if the compression test was ok (when the engine was warm)??

I know everyone is getting sick of HG problems but this one has me stumped. Compression great, runs great (slight rough idle), but major coolant loss with no leaks evident.
______________________

1997 Flaxon 80 - My Baby
22x,xxx great kms + many more (I hope!)

 

[landtank]

get some florecent dye for the coolant and then use a black light to check for leaks. It's possible the leak is small and evaporating on the hot engine before you can see it.

Also a leak down test might be in order.

 

[e9999]

could the white goo be an emulsion of oil and coolant?

 

[sdbrassfield]

White or Tan milky goo collecting on the oil cap is not a good sign. Compression test is in order....

 

[CJF]

could the white goo be an emulsion of oil and coolant?

Absolutely.

White or Tan milky goo collecting on the oil cap is not a good sign. Compression test is in order....

He stated in the first post that compression test came back ok.

IF this is not simply a leak somewhere, it sounds more like a cracked head=coolant into oil. Don't know the definitive test(s) for such a thing, but I'm sure others will chime in. Maybe flourescent dye as recommended, and see if that's what's showing up on the cap.

IdahoDoug had a cracked head on his 97(?). Look for his threads, but I think he caught it by pressure testing the cooling system with the valve cover off, and here came the anitfreeze...

Landtank, Would a leakdown test catch such a thing? I wouldn't have thought so.

Centrex, You may or may not have a major problem. Diagnose carefully, keep very precise records of how much coolant you're going through, how much goo you're getting under the cap, and any other symptoms.

Good luck,

Curtis

 

[MH_Stevens]

And dont's forget the wonderful people at Blackstone. They gave me reassurance when i had almost exactly same symptoms and yet I now seem to be OK. See "Three symptoms appear all at once"

 

[landtank]

It's been stated here many a time that a leak down test is better at detecting HG problems than a simple compression test as it's a time spanned test. I have no experience in using it to identify a problem myself but do trust the people here stating that as fact.

 

[CJF]

And don't forget the wonderful people at Blackstone.

Oh yeah; of course.

Send off an oil sample ASAP.

 

[CJF]

It's been stated here many a time that a leak down test is better at detecting HG problems than a simple compression test as it's a time spanned test.

Agreed, and probably something he should do. I was just curious whether it could catch non-compression related coolant loss issues.

Curtis

 

[IdahoDoug]

If you ever hear/feel a 'catch' in the engine during the first engine revolution while starting, then be very suspicious of a HG. This will only happen when the affected cylinder stops when it is not compressing, which means upon shutdown the pressurized coolant can seep into the unpressurized cylinder. Generally overnight. While starting, the engine will give a single unusual sound or pause as the starter has to overcome the accumulated coolant in the cylinder and then continue cranking over normally as it clears on the first revolution. That's one thing to look for.

Another EXCELLENT (my preferred test) is to rent/borrow a cooling system pressure tester. This goes on the radiator in place of the cap and is simply a hand pump with a guage. Be advised you will need an adapter that I could not find for the common smaller neck. I borrowed a mechanic's unit after being unable to find one for rental. You pump it to 15psi (don't overpressurize needlessly) with the spark plugs out and a flourescent dye in the system. If the pressure does not drop, you've got a good sign. If it does drop, start looking around the engine immediately with the special glasses on and the light (dye/glasses and LED light on flex wand are cheap at most auto stores). Since you bought the flex wand LED light, you can stick it directly into the open spark plug hole and if you see green dye you have your answer. Also because you bought the flex wand, you can actually see the piston tops and be able to see if one is cleaner, AND you can push the little LED light tight up against various hoses and block seams to check carefully for a leak. You'll need a mirror for #5/6. It may take a couple pump up cycles to get enough dye atop the piston where you can see it in the middle as it will dribble in around the edge.

This is best done with a cold engine and a plank across the engine bay from the front engine lift hook to the right fender. Don't put weight on the plastic radiator top tank and compound your fun.

If this is inconclusive, now you've got dye in your coolant and can check the dipstick every day to see if it's beginning to glow. Do this with the engine recently used so the coolant is mixed into the oil if it got in there. Otherwise it may be pooled at the bottom.

Right now, you can also check if the dipstick shows any signs of oil emulsion (oil is tannish and opaque, not brown and clear or dark brown and clear).

So, get the dye kit. I got mine at Auto Zone and it was nice quality for some $18 but they seem to only have this seasonally (summer is radiator problem season).

DougM

 

[centrex]

Thanks again guys.

I will get some dye and try the 'flourescent test' and post back with results. I hope its not cracked or worse!

I am a bit paranoid due to my brother having his head done recently with less on the odo than mine (he had 18x,xxx kms - mine 22x,xxx kms).

They also said that his block had a 'pit' in it and they repaired it. Is this possible??

 

[mobi-arc]

In my '91, it would burn coolant constantly due to a pin-hole leak in the engine block. The truck didn't run hot, never overheated, never blew a head-gasket, and never had milk in the oil. Ran it to 180,000 with no engine or overheating complications, then sold it......probably still on the road.

 

[CJF]

it would burn coolant constantly due to a pin-hole leak in the engine block.

Details? Coolant was ending up where? Side of the engine??

Curtis

 

[IdahoDoug]

Was that someone else's (mechanic) guess as to the constant loss? I say this because a pinhole leak in a cast iron block would be beyond comprehension, especially in a block in production as long as that 4.0's

DougM

 

[centrex]

Took a bit of oil and 'bammo' it was milky. I also idled it for about 10 - 15 mins warm and condensation began to form on the exhaust pipe.

Looks like the head. Hopefully just the gasket and not cracked (fingers crossed).

Major 'white goo' (condensation) again on the oil cap.

Don't prey for me, prey for my baby.

______________________________

'97 80 - My Baby
22x,xxx kms - not so trouble free anymore

 

[IdahoDoug]

I don't fully understand this - 'took a bit of oil'? Also, I can idle my trucks from cold and 10 mins later the exhaust pipe is still dripping condensation - totally normal.

As for the white goo, yeah that's a concern and definitely something to watch, but you make no mention where you live. In my area (NW US) it's the time of year where cold nights and moderate days make for maximal engine condensation. Couple that with some around-town only driving and I think you might see some goo on the oil cap if your PCV valve is aged. As for the overflow tank, did you do some quasi-scientific observation with a piece of tape and daily cold morning pre-start marks on it? It can get low from an external leak or that weak rad cap and now you're just refilling the engine - might fill it up in one more overflow tank fill.

I just don't want you to commit to a HG without real good solid information. Of course oil analysis by most big diesel shops would tell you instantly. As would Blackstone Labs, but it seems your kilometer comments put you in Canada?

Anyhow...

DougM

 

[e9999]

water is one of the main products of combustion of gasoline.
there better be water coming out of the pipe!

 

[mobi-arc]

Don't know. Engine under load, especially in steep inclines, it would smoke coolant which would turn to steam in the engine compartment. Never tore the engine apart to find the problem as coolant is cheap to replentish and an engine tear-down is a costly endeavor. As it didn't impact the reilability of the truck, it was never a problem, just an annoyance.

Details? Coolant was ending up where? Side of the engine??

Curtis

 

[centrex]

Oil I can see in the top under the oil cap (valve cover) and on the dipstick is becoming very milky. Mainly in the vavle cover tho'.

I refill the overflow everyday now but cannot determine when it is actually leaking. Sometimes I go for a drive and there is still coolant in there afterwards, but about 1 hour later of sitting there the overflow is about 2-3cms down again.

I am leaving it at the shop tonight and they will test it cold tomorrow. I figure it is leaking into the engine when the engine is shut off and still pressure in the radiator?? But shouldn't there be coolant out the exhaust when started up?? It is running a bit 'sluggish' when first started in the morning.

I live in Australia where it is about 25-30 deg C and low humidity.

 

[CJF]

Oil I can see in the top under the oil cap (valve cover) and on the dipstick is becoming very milky. Mainly in the vavle cover tho'.

I refill the overflow everyday now but cannot determine when it is actually leaking. Sometimes I go for a drive and there is still coolant in there afterwards, but about 1 hour later of sitting there the overflow is about 2-3cms down again.

I am leaving it at the shop tonight and they will test it cold tomorrow. I figure it is leaking into the engine when the engine is shut off and still pressure in the radiator?? But shouldn't there be coolant out the exhaust when started up?? It is running a bit 'sluggish' when first started in the morning.

I live in Australia where it is about 25-30 deg C and low humidity.

Your problem may have nothing to do with coolant into the cylinders and then out the tailpipe.

As far as "when is it leaking", probably whenever it's running. Even a healthy motor sucks coolant from the overflow to the radiator as it cools, but of course with a healthy motor it won't get any lower than it was the previous heating/cooling cycle.

Have you found Idahodoug's cracked head thread yet??

Good luck,

Curtis