Hydrocarbons in coolant ... but not the head gasket.

**ahorton** · 28th June 2012, 08:58 PM

I love my D2 V8 on LPG (vapour), but oneday the heater core ruptured and it overheated. After that, hydrocarbons were showing up in the coolant and it looked like there was also a coolant leak between one of the heads and the block. However, it did fine on a leak-down test (both hot and cold).

I got the head gaskets off ([ame="http://www.youtube.com/watch?v=yza2zKk7R_M&feature=relmfu"]silly time lapse video here[/ame]) but they are perfect.

Both the block and head look pretty good too. No obvious cracks anywhere.

So I'm now wondering what it might be.

Any suggestions?

**Blknight.aus** · 28th June 2012, 09:18 PM

depending on which vapouriser you have it may have a coolant jacket in it.

**ahorton** · 28th June 2012, 10:19 PM

Indeed it does have a coolant jacket. I took it back to the guys who installed the LPG and they had it for a week. They isolated the LPG system, flushed the coolant and then left the engine idling for hours at a time. The hydrocarbons kept coming.

**clubagreenie** · 28th June 2012, 10:48 PM

Is it causing any issues? If it is it worth worrying about?

**ahorton** · 29th June 2012, 12:25 PM

No it wasn't causing any issues. So I may end up just putting it back together and driving it.

I'll feel silly for having done so much work on it without actually fixing anything. At least I know that everything inside is fine.

**Blknight.aus** · 29th June 2012, 01:03 PM

have you got an in radiator oil cooler?

OR have you or someone else accidentally dropped grease into the cooling system jackets in the past, that stuff is detectable after 4 or 5 flushes if you only do cold flushes.

**ahorton** · 29th June 2012, 11:09 PM

Interesting thought about having dropped grease into the cooling system. As far as I know it hasn't happened but I can't be sure.

My oil cooler is separate to the radiator so I doubt that's a problem.

This would explanation fits in the 'just put it back together and drive it' category.

**PhilipA** · 30th June 2012, 08:13 AM

IMHO It is the head gasket.
I once knew a guy with an F100 ute who spent over $1000 20 years ago having a workshop even pull of the exhaust manifolds looking for leaks.

At the end of the day it was the head gasket and he would have been better off from the beginning just changing the head gasket.
If it quacks etc etc .
Regards Philip A

**ahorton** · 2nd July 2012, 11:42 AM

I took the heads into a machinist last week and hopefully I'll hear what they're like today.

The guy I spoke to reckons he could see some tiny markings on the gasket which suggest that it had started to fail.

So I'm hoping that it really is just the gasket. My bigger fear is that the heads have softened and warped.

**clubagreenie** · 2nd July 2012, 10:49 PM

Are the TD head alloy also?

Reason I ask is that we seem to have the persistant problem of head softening in these and in the V8's they also, if "heat treated" well enough tend to soften the blocks and heads. I was lucky when I did my 4.0 and the heads survived (hardness tested prior to skimming).

Certain toyota engines also suffer similar fates. Mainly the M series 6 cylinders, in particular after they bought in the 7M, secon of the DOHC engines. Notorious for blowing head gaskets. Studs and copper gaskets are the only real solution but the cause is not using the OEM toyota coolant. They run hotter with other stuff and it also seems to have some sort of metalurgical effect on the alloy used for the heads.

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Hydrocarbons in coolant ... but not the head gasket.

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