So I've been losing coolant slowly and it was recommended to do a compression test. Having never done one I was a bit apprehensive, but I decided to go ahead and try one, I think I did it correctly. I drove around 10 minutes, car was hot, took out all the plugs and floored the gas pedal. On the first set I used 4 revolutions and then redid at 6 revolutions to check the max of cylinder 1 and cylinder 5. I went down the line 1-5 on this these tests.

Here they are:



I went for another drive, did it again, used 10 revolutions, and got a max of 195 on cylinder two and only 178 on cylinder 5., which I did tested first. Cylinder 4 was 185 I believe. I can't remember exactly but it wasn't in the 190's.

Thoughts???

It looks OK to me although that last cylinder concerns me a bit. Still OK for 148,000 miles? Do you think I should go get a block tester to check the head or should this rule it out?

I also looked at the heater core casing and couldn't find any indication of coolant loss. No bright green drops anywhere.

 

IMHO the compression results are just fine. You might have some gunk in the rings on 5 and you can JRL it and dump 1/3 of a can of seafoam in with the oil and see if they equalize.

I put a new heater core in my wife's car a few weeks ago and every few days she would let me know that the coolant level light was on. The first couple of times I thought it was just purging the air out of the system but I later found that one of the quick connections at the firewall was not secure. It wasn't really until I let the car cool down that I could find the minor (about to become major) leak was occurring. I had looked for leaks on the core and the connections at the firewall and never saw any when the car was hot.

I fixed the connector, refilled the tank, and the problem is solved. The moral of the story is that some of the leaks don't really appear until everything cools down and the coolant starts to drip instead of spew.

It didn't drip enough to be identifiable in the driveway but I think it lost a fair amount on the road under pressure.

...Lee

PS: Check the gap on #4.

 

I really give it a good look over when hot and cold. I tore into that heater core compartment today, couldn't find any residue or drops. I looked at all the connections, including the firewall. What's killing me is I can't find anything.

It is a very small amount of coolant, over two months the level dropped by 1 cup or so (maybe 1 cm or 3/8" on the expansion tank), that was around 1500 miles of driving. Nothing even remotely close to cause the light to come on. Which is why I don't know if it started losing coolant after the two overheating episodes 7 months ago or when I replaced the hoses back in October. I just can't narrow it down.

Because it's such a slow leak I was just worried that I'd throw all kinds of money toward tests and get nowhere, or that they'd not tell me the full truth.

Also, I know it's not that big of a leak, even if it is a headgasket, but I don't want to continue throwing money into this car if it is a headgasket, because the cost to repair ($1500 or so) will outstrip the cars value since it also needs a new tranny. I want to start collecting 5-speed parts but if this car is on it's way out I want to know now to make an educated decision to sell it or drive it till the engine gives up the ghost, which I hear will happen soon if I continue operating with a bad headgasket which puts coolant in the oil.

 

I agree with Lee about the compression test; that's essentially what i get from my '95 N/A wagon (#5 also a bit lower than the others too) and it's at 160K mls. I have never done the crank counting method though; just crank it until the gauge stops going up is my methodology; but 10X sounds about right.

Regarding the coolant loss; to really do it right, you need to buy, borrow, or rent a coolant system pressure tester. Make sure you get one designed to fit your car.

Then with the engine stone cold, install the tester on the coolant recovery tank, pump it up to 15 psi (note the exact pressure), and then let it sit overnite (24 hours is best). If you come back after that time and the pressure on the tester has dropped by more than 1 psi, you have a leak; ideally it will not drop at all.

At this point (assuming the pressure has gone down) look everywhere for external leaks; if you don't find any, they're probably internal (that's bad). Pull the plugs and crank it (don't forget to disable the ignition) a couple of turns. If coolant sprays out of one of the spark plug holes; bingo - head gasket (or cracked head but the former is more likely).

If you do the pressure test and it doesn't drop pressure, that's good because it means you don't have a leak in the engine. But your rad cap could still be bad; you can test it with the pressure tester as well. If the cap doesn't hold pressure your coolant will expand out the overflow while driving; if you're lucky this is your only problem.

BTW; not to pile it on but your about at the right mileage for the 2nd timing belt; has that been done?

As far as giving up on this car, it really depends on what you want and need out of the vehicle. Mine has a little more mls than yours; i have recently put about $1k into it for regular maintenance stuff (but that's only for parts as I do most of my own work). I drive it every day to work and use it as a utility vehicle on the weekends; still every time i drive it, it makes me

 

Ok guys I threw in the towel, my good natured indie is going to look at it for me, and do the chemical test if he doesn't find anything externally. I want to know, and I trust his findings more than mine, so it's going to be his call. If anything it will put me at ease, or let me know I need to seriously start looking for another car.

Thanks for all your help!

 

Good/bad news...it's not the head gasket but is the radiator, it's got a hairline leak, so I need to budget for that in the future.

The good news is the engine is fine, so I can go ahead with my mx items that need to be done.