Outer Limits 4x4 Board

Here are the symptoms....

Have a 6.2 chev V8 deisel....
Was running sweet until I gave it an absolute floggin up the bush a few weeks ago... high revs and lots of speed work through the scrub...
since then I've noticed a drop in power, have been getting a bit of moisture/wet soot being expelled out the exhaust on start up... never used to do this and is blowing a bit more smoke than it usually did, usually a bit blue in colour in start up and then black when warmed up!!

Now I'm sorta leaning towards a cracked head gasket atm, but unsure how to test this without removing everything to replace it anyway. There are no visible signs of oil in the water and no noticable signs of water in the oil either(I only dropped the oil out yesty for a change to see what it was like)

So I need some pointers to head me in the right direction for a diagnosis of this... to confirm wether or not I do have a cracked head gasket or not... I am mechanically minded and have a few tools at home, if not I can get my hands on some if needed to help with testing things......

Cheers in advance

ant bubbles in the radiator when eng is running and rad cap off

oh n blue smoke = eng oil

black = fuel

Try removing the oil cap while the engine is running and placing a drinking glass over the hole. If condensation forms inside the glass then your head gasket is done. Is the motor running hot?
The symptoms you described could be alot of things. Nothing seems to point specifically to a head gasket though. Then again, Im hardly an expert on diesels.......

v840 wrote:Try removing the oil cap while the engine is running and placing a drinking glass over the hole. If condensation forms inside the glass then your head gasket is done. Is the motor running hot?
The symptoms you described could be alot of things. Nothing seems to point specifically to a head gasket though. Then again, Im hardly an expert on diesels.......

will try this tomorrow or Fri.... and no, not running hot going by the standard toyota guage.. might need to get an aftermarket on to read exact temps to be sure though.

Head gasket could be leaking compression from the cylinder into the oil, check the oil cap for excessive smoke/pressure.
Maybe consider a compression test. It can be done on diesels but only certain places have the right tools to do it. It's not too expensive and it gives you some info in regards to piston ring wear or valves loosing compression on a particular cylinder.

v840 wrote:Try removing the oil cap while the engine is running and placing a drinking glass over the hole. If condensation forms inside the glass then your head gasket is done. Is the motor running hot?
The symptoms you described could be alot of things. Nothing seems to point specifically to a head gasket though. Then again, Im hardly an expert on diesels.......

that's an extremely inconclusive and inaccurate way of testing for a head gasket leak.

A cracked cylinder head or head gasket leak will not normaly cause a lack of power unless it's so bad that it is causing a missifre on one or more cylinders. As mentioned, Blue smoke, oil. Black smoke, partially burnt fuel.

I don't diagnose problems over the internet cause i don't want to make you pull your heads off for no reason. .
My suggestion, take to a mechanic!
Good luck
Cheers Dan

OP asked for pointers on how to look for a head gasket leak. I never said it was foolproof. A TeeKay head check is the best way I know of (Im no mechanic though) but they are pricey compared to the glass method.

I agree he should probably take it to a mechanic but there is nothing wrong with running a few booty diagnostics first. It could very well be something simple.
Just to reiterate, what I dont know about diesels could probably fill several large books so please take anything I say with a grain of salt. I just dont see the point in going straight to the mechanic when the problem could possibly be found and solved without leaving the driveway.

Ok .. im thinking... if there is condensation in a glass over the fillet hole... this MUST be water... right??? if there is water here it MUST be bad... right??

so if there is condensation then it must be a cracked C/H or gasket???
if there isn't there still could be a cracked C/H or gasket??

correct me if im wrong (really)

bu if there isnt condensation from a hot motor, or bubbles in the radiator, or water in the oil, then it CAN'T be a Head(Gasket)???


or have i missed the point?

my mechanic put a pressure test on the radiator to see if pressure would leak out overnight if it did it could mean leaking head gasket

would most leaky head gaskets leak at 15psi???
as compared to combustion pressure?