So about 2 weeks ago my car gets hot. Like 80-90% on the gauge. I then get the car home thinking maybe its a bad thermostat. I replace it and and still gets very hot. Then I think hey maybe the water pump. Replace the water pump and it still runs hot. I try this again without the thermostat in. Still over heats. I check the lines for anything in them, nothing. Maybe the radiator is clogged so i run cleaner through it and some stuff comes out, not much. I put it back in still over heats. I take the radiator to a radiator specialist and says its not clogged. When running I do not smell coolant burning in the exhaust it smells clean. When it overheats it will over heat just idling in the drive way or if i drive it around the block. I have no clue what else to do or look for. Could this be a bad coolant seal?


1987 turbo II
Koyo Rad
e-fan
Intake

 

what makes you think its over heating? Is the temp gauge up? Or is there just over pressure i the water system throwing water out the overflow? Feel the air coming from the fan, Is the heat even. Try using no thermostat see if that makes a difference. If the coolent seals are bad it will over pressure the cooling system. So with the cap off see if there are bubbles coming up as the car is running...

 

I tried running it with no thermostat. It does seem to be very high pressured. but i will check for bubbles.

 

I wouldn't say it's blown coolant seals bud, the system would be pressurized and you'd just lose a **** ton by burning it off as it bleeds into the combustion process, you shouldn't have a problem with overheating until you burn that much coolant out of the system it starts loosing its ability to properly cool the engine. But your exhaust does not give signs of burning coolant as far as I could tell.

But after assuring the fan is working properly, new t-stat, new water pump, rad checked out, plenty of water with seemingly no air pockets, were pretty stumped. I hope somebody comes along with some more knowledge and a better idea, to help ryan out.

 

They sell a test kit to test your cooling system for traces of combustion gases. It's called a "Block Tester". Then you can be sure you have blown coolant seals.

 

couldnt see bubbles in the radiator, car only runs for about 10-20 minutes until it is over heating. not sure what else to check?

 

still looking for some more help, thanks

 

any one have any ideas? still cant figure it out.

 

It could be air in the system. it can be a bitch to get it all out, especially if you have an aftermarket s4 rad and it doesn't have the little bleeder screw.

get this special funnel:

http://www.amazon.com/Lisle-22150-Sp.../dp/B0002SR6WK



I use it all the time. You run the engine with that funnel threaded into your filler on the rad and sealed with a rubber washer on the adapter fitting they supply. The funnel is filled with coolant. As the engine runs, you can physically see all the bubbles escape into the pool of coolant in the funnel itself. I highly recommend you try this before you pull the motor, take it to a shop, or do anything else expensive or time consuming.

 

Yes I do have an aftermarket koyo radiator that does not have the bleeder.
Thanks, I just order the funnel. Hopefully that will work.

 

Wow, local Rotary love! I'm in Warrior's Mark (Between State College + Altoona).

Either way, to try to help... I'd do an inspection on the back heater hose connecting from the block to the throttle-body area.. I had one crack on my old NA, and I had the same symptoms, it was just leaking enough that it wouldn't build the pressure needed, and the little bit of coolant was running down onto the exhaust side of the back of the engine and evaporating without a trace...

Maybe we can meet up and I can try to help you out? I sent you a PM with my contact info.

 

Alright thanks man. I know where that is. Nice to find someone else in the area thats into Rotaries! We will be in touch for sure.

 

possibly try replacing the $20 water thermo sensor on the back on the waterpump housing too if you still cant figure it out