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Hi all my newly rebuilt 85 has started filling the over flow coolant res up to the very top and boiling after trips on the freeway. Granted i push a little hard in 4 and 5th gears but while breaking her in she was fine barely even was getting hot. So now ive noticed that radiator stays relatively cool hot mind you but cool in comparison to the hoses and the rest of the system. Couple things ive noticed cooling sensor harness wires broke during removal for the rebuild they had to be spliced back together. Can the increased resistance in the wires have a major effect on the system as a whole. Also temp guage is kind of intermittently working and not. Does that sensor directly impact the guage or is there something in between that controls the guage? And last thing i noticed when re installing wire harness loom two wires both blue with pink dots or marks or whatever you wanna call it. Basically solid blue with pink they are grouped with the part of the loom that the starter fusable link wire, coolant sensor, and one other wire that i also was wondering about it looks like a ground wire its got white insulation and a ring to put around a bolt. I was thinking maybe it was the ground for the starter but read here somewhere that the starter is grounded through its mounting bolts so then i thought maybe it was the ground going to bell housing of transmission but i still dont know one way or the other. The photo above is of the two blue wires i was talking about. As it stands now i just have them kind of tied off to the side havent even checked em for voltage yet.
 

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as far as the cooling systems ability to get rid of heat an overheating problem could be caused by a bad thermostat, the radiator fans are controlled by the temperature sensor in the radiator so only thing those wires do is communicate with the ECU i belive
 

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...rebuilt 85 has started filling the over flow coolant res up to the very top and boiling after trips on the freeway...

...i push a little hard in 4 and 5th gears but while breaking her in she was fine barely even was getting hot...

... cooling sensor harness wires broke during removal for the rebuild they had to be spliced back together. Can the increased resistance in the wires have a major effect on the system as a whole....

...Also temp guage is kind of intermittently working and not. Does that sensor directly impact the guage or is there something in between that controls the guage?
There are a number of reasons why your coolant will blow:
Air in the cooling system. Make sure that the system is properly bled out before you do anything else. Do it by the book. If you have bled the system and this recurs, then it is possible that you have a leak. Even a small leak will allow air to accumulate, because the system goes to vacuum as it cools off.
Ruptured head gasket. That can allow combustion gas to blow into the coolant, which has the same effect as trapped air. This may have the characteristic that it doesn't happen until you open the throttle fully.
Defective pressure cap. That can allow the coolant to boil even though it has not overheated.
Defective thermostat or plugged radiator. If this is the case, you should see the engine overheat before the coolant blows.
Incorrect coolant mix. Not enough antifreeze will allow the coolant to boil at normal operating temperatures.

This car has a vast excess of cooling capacity. If the system is working right, it won't matter how hard you push the car.

No.

The temp gauge is completely independent from the cooling system and engine controls. It has its own sensor and wires. If the gauge fluctuates intermittently, it could be the gauge that is bad. Otherwise, it is evidence for large bubbles in the coolant.
 

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... the radiator fans are controlled by the temperature sensor in the radiator so only thing those wires do is communicate with the ECU i belive
That is correct, except that the temperature sensor communicates with the AC controller. The fans serve both the radiator and the AC condenser, and the AC controller performs the integrated control function. If the car does not have OE AC, then the sensor controls the fan directly through a relay.
 

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That is correct, except that the temperature sensor communicates with the AC controller. The fans serve both the radiator and the AC condenser, and the AC controller performs the integrated control function. If the car does not have OE AC, then the sensor controls the fan directly through a relay.
Ahh okay, both my cars are equipped with factory AC so I haven't been exposed to that nuance difference between models.
 

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Ok so there is factory ac although ive removed the belt because the refrigerant discharged years and years ago. The car did overheat a few days ago and the guage worked then telling me i was screwed i probly did all the wrong things but i opened the valve on the radiator and the one for the core in the frunk. Very little to no air in either then burped her and added more coolant the existing has a slight tint of brown to it but im certain its from radiator the car sat for six years until i did the revuild so i know its got to have lots of rust inside. No coolant in the oil im pretty sure no oil in the coolant cant smell gas in the coolant and the build is so fresh i hate to even toy with the notion of hg problems. If the tstat were stuck closed is it possible that the system after the tstat is dry due to all the coolant prrculating into the overflow. I know that when pressure builds it pushes coolant into overflow and then as it cools its sucked back into the system. Just how full should the overflow get and the boiling im pretty sure seems to be from air blowing out of the system. Im babbling here sorry. The two wires i was referring to does anyone have a certain answer as to where they could be from ? And last thing although rhere is so much more but oil pressure guage when i turn the car to on the guage goes all the way up and when i start rhe car it goes all the way down and stays there. I fairly certain (obviously cant say totally certain otherwise i wouldnt ask) its got good oil perssure .
 

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Discussion Starter · #8 ·
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So this is how the coolant looks granted these photos wont do it justice but you cannsee in the first one the sediment from rust has collected on the bottom and the coolant does now seem to have a slightly milky appearance
 

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I will check my car tomorrow for what those wires seem to go to. although you should also be bleeding air out of the bleeder valve right on top of the thermostat housing. and those pictures just look like rusty coolant that can be flushed out with a few coolant changes. although something just came to mind, if you have the factory steel radiator then it is possible that the radiator cores are rusted/corroded and you're not getting flow through the radiator or you're getting very little flow.
 

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Discussion Starter · #11 ·
I will check my car tomorrow for what those wires seem to go to. although you should also be bleeding air out of the bleeder valve right on top of the thermostat housing. and those pictures just look like rusty coolant that can be flushed out with a few coolant changes. although something just came to mind, if you have the factory steel radiator then it is possible that the radiator cores are rusted/corroded and you're not getting flow through the radiator or you're getting very little flow.
See that is what im thinking and it is the factory unit ive been thinking to replace it with an after market aluminum unit but a little unsure of things
 

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the little white piece there is your engine bay bleeder it'll bleed any air coming from the radiator going back to the engine, it is crucial that this bleeder is bleed correctly otherwise you will absolutely have overheating problems because air will get trapped behind the thermostat and then get trapped in the engine block.
 

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I would try bleeding the system again making sure to hit all the bleeders attached is a copy of the aw11 service manual you can reference the manual to get a perfect textbook coolant bleed, if that doesn't work you can test or replace the thermostat and if that doesn't work you can test or replace the radiator.
 

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Discussion Starter · #15 ·
I would try bleeding the system again making sure to hit all the bleeders attached is a copy of the aw11 service manual you can reference the manual to get a perfect textbook coolant bleed, if that doesn't work you can test or replace the thermostat and if that doesn't work you can test or replace the radiator.
Thank you sir i will report my outcome time is valuable and i appreciate yours.
 

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Discussion Starter · #16 ·
well did the cooling system to the t and been burbin her all day i think i must have a leak somewhere because the itsy bitsy teeny weeny little fucking air bubbles keep coming its all from the upper rsdiator valve i think there must either be blockage in there so thats why so much air trapped as it just keeps trickling past thd blockage so does the air or there is tiny little leak in the system. i just took it to the i just hit the freeway fof a little while then through town then i raced around a bit got back and she looked like a witch making potion all bubbling and gurgling i opened the valve on the radiator and a huge bubble of air came shooting out. i guess all i can do is keep on and keep trying to burb the little ficcal little you know what. right ? how long before i can be certain to loik elsewhere for the problem
 

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View attachment 76304 View attachment 76304 Hi all my newly rebuilt 85 has started filling the over flow coolant res up to the very top and boiling after trips on the freeway. Granted i push a little hard in 4 and 5th gears but while breaking her in she was fine barely even was getting hot. So now ive noticed that radiator stays relatively cool hot mind you but cool in comparison to the hoses and the rest of the system. Couple things ive noticed cooling sensor harness wires broke during removal for the rebuild they had to be spliced back together. Can the increased resistance in the wires have a major effect on the system as a whole. Also temp guage is kind of intermittently working and not. Does that sensor directly impact the guage or is there something in between that controls the guage? And last thing i noticed when re installing wire harness loom two wires both blue with pink dots or marks or whatever you wanna call it. Basically solid blue with pink they are grouped with the part of the loom that the starter fusable link wire, coolant sensor, and one other wire that i also was wondering about it looks like a ground wire its got white insulation and a ring to put around a bolt. I was thinking maybe it was the ground for the starter but read here somewhere that the starter is grounded through its mounting bolts so then i thought maybe it was the ground going to bell housing of transmission but i still dont know one way or the other. The photo above is of the two blue wires i was talking about. As it stands now i just have them kind of tied off to the side havent even checked em for voltage yet.
After painstaking attention to detail rebuilding my 4age, it exhibited the same boilover issue traced to a blown head gasket (500 miles on the engine). After removng the head, I thought I had simply acquired a bad head gasket. Further checks revealed that the head bolts were bottoming out on rust deposits at the bottom of the holes so my apparent torque readings were bogus. I cleaned the threads and bolt holes with a bottoming tap and installed an ARP head bolt kit - problem solved.
 

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Discussion Starter · #18 ·
After painstaking attention to detail rebuilding my 4age, it exhibited the same boilover issue traced to a blown head gasket (500 miles on the engine). After removng the head, I thought I had simply acquired a bad head gasket. Further checks revealed that the head bolts were bottoming out on rust deposits at the bottom of the holes so my apparent torque readings were bogus. I cleaned the threads and bolt holes with a bottoming tap and installed an ARP head bolt kit - problem solved.

ahhhhhhhhhh ****
 

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Discussion Starter · #20 ·
as far as the cooling systems ability to get rid of heat an overheating problem could be caused by a bad thermostat, the radiator fans are controlled by the temperature sensor in the radiator so only thing those wires do is communicate with the ECU i belive
I did in fact trace them back to the ecu but the ecu is only one end i have yet to find what theyre supposed ti be attached to.
 
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