Mike's 85 FWD 5dr Tercel

[irowiki]

Could also be a slight leak somewhere.

Pinhole in the rad, and check the bypass tube.

[dlb]

assuming there are no external leaks (even pinhole leaks will leak drips or puddles once the engine is warmed up and idling), i'd agree that you HG is on its way out. that's pretty minimal though so i might try a 'head gasket in a can' fix. some have good reviews.

[Notmikeb]

No leaks while idling. If it is an external leak it only happens while driving I guess.

[irowiki]

I had a tercel leak at the bypass tube orings but never leave a puddle or drips, but still used an overflow's bottle worth of coolant every 500 miles if I recall.

[Notmikeb]

Hmmm. I just replaced those when I did the water pump and timing belt in July. Used some silicone to seal it up too. I'll try wiggling it while the engine is running see if I get any visual leaks.

[irowiki]

Oh, if you replaced those already you're probably fine. You'd know because there'd be nice green coolant pooling where the bypass tube enters the thermostat housing.

What about your heater core?

[Notmikeb]

Blowing hot air. No puddles on floor. Both good signs I guess?

[Petros]

I have driven on compromised head gaskets for up to a year. you will have several weeks at least if you do not allow it to over heat. check it everyday and perhaps keep a log of how much you put in and the miles. If it gets worse you know you will be running out of time. If it is not using too much, you can keep driving it for now, but do not let it run low.

At some point it can fail all at once, so it is best to 1) confirm it is actually the head gasket (inspecting the piston top is the best way, you can see it through the spark plug hole when it is a top dead center), compression tests will not show a problem if it just leaky., 2) than get the parts ASAP and at the next convenient chance you get replace the head gasket.

It is just as well you drive it at least a bit more to confirm it is the head gasket.

Good luck.

[irowiki]

With compression that good it just doesn't feel like a head gasket issue for me.


How long ago have you worked on the coolant system it may have just been bleeding air out

[Notmikeb]

It's been 2 months and maybe 1500 miles since I did the thermostat. I think I'll take Petros' advice and just watch it like a hawk but keep driving. If it is the head gasket, hopefully it waits until the weather warms up as I don't have a heated garage. If it's another leak, maybe it will make itself more apparent and easier to diagnose.

[marlinh]

A small coolant leak can be hard to find. Check around all the hose clamps for slight moisture. The water pump could be starting to leak and still not drip on the ground. You will just see a dark stain at the drain hole behind the bearing. You might be able to see it with a mirror and a light, although I sometimes have to remove the water pump pulley to see it effectively. If the transfer tube is leaking it usually puddles at the bottom. I wouldn't wiggle it around, that could break the seal.

[Notmikeb]

Found it. Upper radiator hose was slightly damp under the hose clamp. I wrapped the end up with a paper towel and took the car for a drive to get it warmed up. Sure enough, after 5 miles or so I stopped to check it and it was leaking out at the clamp. I guess it wasn't leaking bad enough to pool anywhere it just evaporates. The hose ends are slightly swollen and flare a bit after the clamp but it didn't seem terrible so move left it alone until now. Autozone has one for $7 so I'll pick that up and swap it out today.

[Petros]

the upper hose is under more pressure than the lower one (that is the suction side of the pump). when it swells it means the internal cords are starting to break down. it is very important that that upper hose is always in good condition. if questionable at all it should be replaced.

I made the mistake of just inspecting this upper hose on my daughter's CRX, when I was replacing other hoses, belts, etc. when servicing it. I did not know how old it was, but it was pliable and not swollen, looked fine. less than a week later when she was crossing the Texas desert on her way back to Austin the upper hose blew out all at once (like a hand grande, totally schreaded). It quickly overheated and did severe engine damage to the all aluminum head and block. I drove out to meet her and see if I can fix it, after getting the head off in a cheap motel parking lot (in 104 deg heat), I found the head had actually melted. We pulled the CRX back to Austin with my Tercel4wd, and I got another engine and rebuilt it, the old one went to the scrap yard.

It is not worth the risk to run on questionable radiator hoses. Although I have allowed the lower hose to be old on many cars if they look okay, the upper hose I have gone to replacing on a regular schedule like all the other parts that wear out.

[Notmikeb]

Replaced it today. We'll see if that was indeed the culprit.

[lannvouivre]

after getting the head off in a cheap motel parking lot (in 104 deg heat), I found the head had actually melted.

Nice! You should have made something with the melted parts. Like some ugly scrapper furniture. I saved all my old 1ZZ pistons for this type of thing.