Possible head gasket failure?

How-to's and repair secrets for your 4WD can be found here. Have a question? Ask it in here!
Post Reply
cars-guy
Member
Posts: 30
Joined: Fri Feb 23, 2018 1:32 pm
My tercel:: 1984 Tercel SR5

Possible head gasket failure?

Post by cars-guy » Mon Dec 17, 2018 2:09 pm

I have an 84 tercel with the 3a engine and 225k miles on it. Just got back with it after a 3,000 mile road trip. Pulled the plugs to check compression and just get a good idea of what the engine is like internally. The spark plugs were replaced before the trip and after pulling them the number 1 spark plug I noticed it had a lot of chalky white build up all over it. The other plugs appeared to be running a little rich but otherwise fine.

Here are the compression readings for each cylinder
#1 = 130 PSI
#2 = 150 PSI
#3 = 150 PSI
#4 = 165 PSI

The car runs just fine and has no issues at all and I've been scratching my head at this for a while. There is no coolant loss at all, there is oil loss but it leaks a bit as well.

Here is what the 3 spark plugs that look ok look like
Here is the number 1 spark plug. It had a lot more of that chalky build up, before the photo was taken I scraped some off
any input would be greatly appreciated
You do not have the required permissions to view the files attached to this post.

User avatar
Petros
Highest Ranking Member
Posts: 11336
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: Possible head gasket failure?

Post by Petros » Mon Dec 17, 2018 11:08 pm

your head gasket is likely fine. if you suffer no coolant loss, there is no indication of a compromised head gasket from either compression or the spark plugs.

looks like the front plug is getting more oil, it has an oil residue on the outter edge, and the white is burnt oil choke build up. the other plug is "normal" appearance. There is no reason to be conserned with any of this, with that many miles on the engine this is actually all within normal wear. The lower compression is likely worn exhaust valve seat.

Either you have a bad valve seal on the number one exhaust valve (likely) or for some reason the front rings are more warn (the #one cylinder runs a bit hotter than the others because the hottest coolant goes out the engine at the front of the engine),

Usually adding a can of Restore to the engine oil will reduce oil consumption and is a good enough repair for now. An oil adaptive like STP might help too. After running the Restore at highway speeds for a day or so, you might check your compression again to see if there is improvement.

There is a repair guide showing how to replace a valve stem seal without pulling the head. But if were mine, I would not bother until it became more of a problem.

if for some other reason you need to remove the head in the future, that would be a good time to have the valve seats reground, and replace all of the exhaust valves with new ones, and install all new valve stem seals. But this is not severe enough to get it done any time soon (unless you plan a major engine rebuild anyway).

Good luck.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

cars-guy
Member
Posts: 30
Joined: Fri Feb 23, 2018 1:32 pm
My tercel:: 1984 Tercel SR5

Re: Possible head gasket failure?

Post by cars-guy » Fri Mar 22, 2019 9:31 am

Petros wrote:
Mon Dec 17, 2018 11:08 pm
your head gasket is likely fine. if you suffer no coolant loss, there is no indication of a compromised head gasket from either compression or the spark plugs.

looks like the front plug is getting more oil, it has an oil residue on the outter edge, and the white is burnt oil choke build up. the other plug is "normal" appearance. There is no reason to be conserned with any of this, with that many miles on the engine this is actually all within normal wear. The lower compression is likely worn exhaust valve seat.

Either you have a bad valve seal on the number one exhaust valve (likely) or for some reason the front rings are more warn (the #one cylinder runs a bit hotter than the others because the hottest coolant goes out the engine at the front of the engine),

Usually adding a can of Restore to the engine oil will reduce oil consumption and is a good enough repair for now. An oil adaptive like STP might help too. After running the Restore at highway speeds for a day or so, you might check your compression again to see if there is improvement.

There is a repair guide showing how to replace a valve stem seal without pulling the head. But if were mine, I would not bother until it became more of a problem.

if for some other reason you need to remove the head in the future, that would be a good time to have the valve seats reground, and replace all of the exhaust valves with new ones, and install all new valve stem seals. But this is not severe enough to get it done any time soon (unless you plan a major engine rebuild anyway).

Good luck.
Its been a little while but I drove the car from la to denver right after my post. Engine would barely run at all after i got there and the compression on the number 1 cylinder dropped from 130 to 105 from the drive. The weber I put on the already tired motor may have been to blame but man is that weber good! Instead of only having power from like 2800 rpm to 4,000 the thing starts pulling at 1800 keeps making power well past 5k although i try not to push it past 4500 if i don't have to. I changed the oil and added a can of restore hopping for a miracle and a miracle it did do. after almost another thousand miles on the car it stopped burning oil and all cylinders are up to 150psi. Amazing stuff

Post Reply