Heating up under WOT

[Highlander]

OK, so the Yo d'or is running fine, no knocking around corners thanks to new struts, shocks and axles. Now, when I climb through the canyon to go home (3000'+ elevation gain) up the steepest part under WOT, I have to turn the heater on to keep the temp needle out of the red. As soon as I'm out of the steep portion and can back off of the throttle, it cools right down and I can turn the heater off. I wouldn't mind this in the winter, but its been in the 90s and that's not a good time to have the heater blasting.
As I see it, there could be a number of possibilities- Head gasket leak (I've already re -torqued it- no help) plug in the radiator (I could change it out with the new one in Yodeux), or restriction in the block itself. I've already put a 180°F thermostat in it and replaced the water pump. It warms up very quickly compared to the other two tercs, but doesn't heat up excessively until it's under WOT. I checked on having my other head rebuilt and got a quote of $280-I only paid $500 for the car in the first place! Any thoughts from anyone? TIA

[splatterdog]

The cooling fan is working right? Is the radiator clogged/missing fins? Does the lower hose feel cooler than the upper. Any coolant loss? How about WOT on level ground?

Engine running good? Why do you need WOT? Do you hillclimb on your way home?

Ever have rusty coolant? 2 of my tercs had mud and prestone supercleaner helped the entire cooling system tremendously on both. Engine temps are way more stable and heater output got acceptable on one and hurt hot on the other.

If you have a sensitive nose, the coolant will have a tailpipe smell if you have a combustion leak.

Other's have mentioned the importance of OE stats. Can't argue toyota quality but I have had no problems with stant's "superstat" in mine.

[Highlander]

Upper and lower heater hoses are both hot, no rust in system, coolant loss through overflow tank, no bent fins, I haven't tried blowing the rad out with compressed air though and cooling fan is working. Can't run far enough under WOT on the flats to get it to overheat (Speed limits, don't you know). Yes I hillcllimb going home- I work at 5200' elevation, and live at 9000'! The pitch in that part of the canyon is ~10% and it's about 2 miles long. I really hate to be the plug in the road, if I back off the throttle, I wind up doing ~20 mph at the top of that section and people are crawling up my %*#! The engine runs well, though it sounds almost tinny compared to the other tercs, which don't have this problem.

[takza]

coolant loss through overflow tank,

Start it up cold...take the rad cap off...start it up...look for a stream of bubbles? These can be very small.

Usually indicates exhaust into coolant. Overheats because...exhaust is hot. It is also corrosive I think.

[splatterdog]

The lower hose should be cooler. Try pulling the fan switch connector while the engine is hot and running. This will turn it on. After the fan has run for a minute or two the lower hose should be noticeably cooler. This will give you an idea on the rads heat transfer capability. A cheap infrared can measure temps the easiest and find any hot spots you might have.

Just checked. Idling hot, my 85 has a 20 degree drop at the lower hose after the fan shuts off on its own.

If it's not 20+ years old, you might want to measure your O2 sensor voltage under WOT. Give you a quick idea if you have carb related issues. Maybe also check for restricted exhaust.

Tested or replaced the cap lately?

How about an amish buggy warning triangle?

[ARCHINSTL]

How about an amish buggy warning triangle?

Well -
This is what my suburb of STL, Kirkwood, installed just before the hill near my house...
Tom M.
>>> Mea culpa to highlander for hijacking his thread, but I just could not resist...

[keith]

Had the same problem when I got our Tercel. My sister had put a lot of money into this problem, double core radiator etc. All it took to fix it was a new radiator cap. You would be surprised how often this is over looked.

[ARCHINSTL]

I had a milder prob back in January with rising temperature (but not to HOT-HOT) when cruising on the highway...I took keith's advice on replacing the cap - voila! - problem solved !
Frankly, I did not think it was this - guess I was remembering waaay back when good caps lasted longer than 2 years...
Tom M.
P.S. The thread, if you're interested, was started by ptothej: https://tercel4wd.com/forums/viewtopic.php? ... emperature

[Highlander]

Hey Tom, Is that Horse towing YOUR Terc up that hill?
OK, well it sounds like using the IR temp gun from work and changing the rad cap may do the trick- I'll let you all Know Thanks to everyone for the input, Splatterdog- the Ox sensor is NEW, but it could still be a plugged cat- it came off of the wrecked '83 and as far as I know it's an original. It passed emissions, though, even after they reduced the passing levels by 50%!!

[ARCHINSTL]

Hey Tom, Is that Horse towing YOUR Terc up that hill?

Shhh...
Goldie does not have access to the computer...although I was sure I'd have to call on my one-horse towing service a couple of weeks ago...

Incidentally - if you have to install a new converter- don't throw it away as did I in '05 - this was before I discovered that it would be worth bigga bucks on eBay - if you are unfamiliar with the bucks, just do an eBay Search...
A friend of a dotter has a good-sized general repair shop here - he would not give away the exact amount of dollars the shop gleaned from the scrap value of replaced converters, but said that it was WELL into 5 figures - and sub rosa dollars, at that...
Tom M.

[Highlander]

Radiator Cap it was! Thanks to all who had suggestions, It's been so long since I had to diagnose an overheating problem that I'd forgotten how important system integrity is. . now to get it aligned and everything is good.

[jetswim]

The scrap 80's Toyota converter is worth between $100 to $200. Make sure the mesh inside is intact though as that's where the platinum/paladium is.
When I removed the cat from my 85 corolla it was completely gone making it worthless.

[Neu]

The scrap 80's Toyota converter is worth between $100 to $200. Make sure the mesh inside is intact though as that's where the platinum/paladium is.
When I removed the cat from my 85 corolla it was completely gone making it worthless.

still try though, I've head of people buying even gone ones for 50 bucks or so.