92 Loyale mystery overheat

[paulpicard]

Well, I am really puzzled by this one. My EA82 (5-sp 4wd.) wagon has run flawlessly since I got it 3 years ago, and did the usual t-belt, EFI, ignition, t-stat, hoses etc. servicing. It's now at 320,000 KM. Still has good compression, and no external coolant leaks. Yet suddenly last week it used up a gallon of coolant in 40 highway KM (level road, 3000 rpm cruise), and another gallon when we decided to head back home. Thankfully all the gauges still work, or I might have missed the overheat signs. I left it sit for 3 days (on fresh snow) looking for green spots - none. Today I pulled plugs - all look fine and identical.Checked oil level, normal, no evidence of coolant in oil. Checked for excess play on waterpump shaft - no play. Refilled rad, ran it till t-stat opened, watched for excess white exhaust (none) and drove it around for a half-hour, then parked and checked for new leaks - none. I do have compression testers, but don't have a pressure test rig, so before I head for the local shop does anyone have any ideas on this?

[john in KY]

Pinhole leak in one of the heater hoses?

[maozebong]

does your heater core leak all over the floor?

 

can you smell it by the tailpipe, or in the engine compartment?

 

i had a pinhole leak on one of the throttle body heat lines and i never saw coolant on the ground. it would pool up on the top of the block and make that familiar smell of it burning.

[paulpicard]

Thanks guys. Heater is fine - no leaks in cab, no coolant smell, dry carpet. I'll pull the spare and take a close look at the hoses and other lines that run over top of the block. Also, I have and use a block heater, but only on those mornings when it's colder than -10C then only for a couple of hours. I wonder if that could be a source of leakage - never see it driving down the road. Do those things tend to loosen up over time?

[paulpicard]

OK, found a VERY small leak - lower right rear corner of the rad (a reman, according to the tag on it) just under the draincock. I needed a strong flashlight to see it - a shiny spot of paint in the middle of the usual gunk covering the lower reaches of an old Soob. I'll try some (recommended) stopleak in there for now, while I scrounge another good rad. If you have a caution regarding stopleak stuff and EFI sensors, let me know, please! Anyone else with the same problem, do use a strong light around the bottom of the rad if you can't find any other sources.

[paulpicard]

Well, the stopleak sealed the pinhole, but yesterday the rad sprung another leak, this time on the front side of the lower right corner. It seems to be at the tank seam, so I'll be ordering a new rad. Meanwhile, the coldstart sensor has failed since I did a compression test. Co-incidence, or somehow connected to the use of the "Irontite" stopleak stuff? It'll start but you need to treat it just like a carb with no choke for at least 2 minutes, then the c.e. light goes off and the i.a.c. starts working. Any comments on that? Could the Irontite have affected a sensor?

Also, I've been quoted $220 for a new rad from a couple of different sources. Been a while since I've bought a rad. Any comments on the price?