New overheating problem

[Ivan141]

Guys, I need to drag this thread up from the cemetary.. My car is having overheating problems that I cant put my finger on lately.

It will not loose coolant as long as I drive normally, but after about 10 minutes of traffic jam it will start overheating, and looseing coolant.

I cant spot any serious leak, no puddles under the car, nothing obvious when running at idle. Turning the heater up to max doesnt seem to help either.
Today it happened again, so I turned the engine off as much as possible , but still it would shoot right up again after a short bit of crawling speed.
It ran normal temperatures once I got moving normally again.
I checked the coolant reservoir as soon as I got home, it was pretty damn high. I dont notice any oil or bubbles in the coolant though.

Any ideas? Thermostat is about 2 years old, waterpump is new and on the car since last summer.
I'm thinking it's either the thermostat, or maybe the radiator cap...possibly BHG, but not likely, it doesnt smoke much either.

[Mux213]

Best to just start a new topic Ivan, no need to revive such an old topic if it didn't prove handy to solve your problem.

No idea what could be causing your troubles though, maybe a broken thermostat and that driving wind is enough to keep the engine cool enough which would explain why it only overheats when standing still for long periods of times? Maybe the thermostat only opens partly?

[Ivan141]

Sorry, I should know better, just thought it might spare us making the same old discussion all over.
I would think it would overheat on high-speed highway drives if the thermostat was stuck, but I can drive 150-160km/h non-stop without any problems.. it just really really hates traffic jams that last longer than 5-10 minutes. I also noticed that when it overheats, it gets worse when i give it more throttle.. which points me toward the headgasket a bit more.

[Mux213]

Very true.

actually, the weird thing is that your troubles sound more like the fan is not working (properly). Thing is, when you're driving the driving wind does a very good job cooling the coolent in the radiator and thus cooling your engine.

When standing still your fan takes over this job. If its not doing its job well the radiator can't loose its heat...

On the other hand, its friggen winter so the cold air outside should be enough to provide cooling...

Someone I can't see how the headgasket could be the problem, I would say that would make matters worse during driving wouldn't it?

[jamiemirror]

Did you keep stock fan shroud ?

[domi]

Sounds mainly like fan issues. Check the fan, the repair manual has to have instructions...

[NoHachi]

My little KE was doing the same thing. Fine on freeway speeds, but after being warmed up hated to slow down again. Shortly after, she started puffing great big clouds of smoke..bye bye BHG.
I do believe that the underlying reason was a thermostat failure though..possibly in combination with the cap failing and dumping most of the fluid in one big swoop.

[Red]

Only two possibles, Ivan.

You know the coolant is being lost after everything is thoroughly heated up. So...if you are lucky it is just the radiator cap. If you have the same crappy anti-leak antifreeze that most of the US is floded with, there can be scale under the cap, so remove it, clean thoroughly, make sure it is seating well. Any radiator shop can test the cap because sometimes they fail and let coolant out--in which case your overflow bottle (you do still have it, yes?) will be too full when you pull over while the car is still hot. (It will be sucked back in as soon as the car starts to cool, don't wait.)

If the cap is more than five years old, it pays to replace it anyway. Make sure the new one is the same pressure rating as stock.

If it isn't the radiator cap...that means something on the engine is heated up and warping or opening up. Usually that would be a loose head or bad headgasket. It could be a bad water pump housing. Easiest way to check that is to clean the engine (steam clean if you can), let it dry, and then dust the likely places with talcum baby. Not "baby powder" made with cornstarch, but real talcum powder aka talc.

The talc is white and easy to see. After you make another run...if anything was leaking it would leave trails where it leaked, also easy to see. No need to wash off the excess talc unless you want to-- it helps protect rubber parts and there's nothing that eats it, etc.

If there are no outside leaks...that leaves the headgasket. Exhaust and compression checks, or sending out an oil test sample to see if there is excess coolant in the oil, might turn that up.

Did you do any work on the head on this engine? And if so, torque it and then retorque it after it settled in?

[Ivan141]

No headwork done.

Your right about the coolant level.. it was too high last time I checked.
Weird thing is the radiator does not get really hot as I'd expect it too.
I can easily touch it after an hours drive, while it should be hot enough to almost burn my fingers if I recall correctly.

The fan still looks like it's turning, but it doesnt generate much of a draft. But then again if the radiator does not get hot enough, the viscous clutch wont be engaging either I think.
I've rarely seen ae86's with the original radiator shroud around these parts BTW, I never had one and it was never a problem before.

[Red]

Ivan-
If the radiator is not getting hot, that could be from radiator cap failure. If the cap opens too soon, the radiator overflows as soon as it heats up, instead of getting hotter as the coolant is pressurizing and contained.

In theory the fan shroud and the air intake snorkel all were designed to funnel air through the radiator and around the engine (instead of over it) so the entire engine is cooled better. In theory.