Hi again, all.

It's been a rough couple months here at Casa Tomlin, and this was the topper for me so far.

#6 is misfiring, my heater core is broken - losing about a quart of coolant every 25 miles or so at highway speeds, and I have water vapor from the exhaust.

One mechanic at Meineke (a former Jag mechanic, in fact) said he compared compression on #6 to the other cylinders and they're all about the same. "Maybe a fuel injector".

Dealer Jag mechanic says I have hydrocarbons in the coolant and coolant in the oil, it's either a bad head gasket or a cracked block. He posited that perhaps the pressure of the leak caused the failure of the heater core plumbing. (?) That'd be a first for me.

I don't know of a way to tell if it's a head gasket failure or a cracked block without tearing at least the top off that side. Lacking both the time and tools anymore to even try it myself, that'd be a lot of money to verify it's a cracked block or not.

Anyone here know of a way to figure out which it is without tearing it down?

TIA.

 

First comment from your description is a head gasket but it could be more. Few cracked blocks but there are always the possibility.

Very good possibility!

Compression test as a first step.

 

What tests have been performed and what are the results?

Has anyone performed a compression or leak test? What is the condition of the spark plugs in the suspect cylinders?

Did anyone drain the engine oil to look at the condition?

Has a pressure test been performed on the cooling system after a cold soak? Are there any external coolant leaks?

If the engine is disassembled, did anyone check for cracks to the cylinder head by means of a pressure test on the casting?

There are other tests can can be performed in addition to those listed here.

 

I'm looking for a way to determine if it is a blown head gasket or a
cracked block without disassembling the motor. It still starts easily, still
runs - although roughly due to #6 misfiring - and only leaks coolant when
it's running.

It doesn't seem to have any steam at all coming from the exhaust when
hot, and not much when cold, more like a cool humid day. And
the smell of coolant in the exhaust is mild at worst: not even sure I am
smelling it.

I've had other vehicles with a blown head gasket that seemed and smelled
far worse. Looking at $6K in repairs, so I want to make sure I'm doing
what needs to be done. As a disabled vet, I can't do much heavy
"mechanic-ing" anymore, so that's kinda out for this one.

 

I think the only way to be sure is to take the head off.

 

Art,

Unfortunately without any signs of external leakage, all the testing in the World will at best only give a probability of the cause.

On the many reported similar instances in the forum, the vast majority have been heads. However, the only way to be absolutely certain is by dismantling and direct examination.

Graham

 

If the spark plug looks like it has been steam cleaned it is a head gasket.