Corrado Vr6 overheating

[mattyd6892 10]

Hi Guys

 

Just recently purchased a 1993 VR6 corrado. My dream car and abit of a project, Had it for a week but developed a fault and wondered from experience on here what it could me

 

The temperature went above 110 degrees and steam out the bonnet. lifted up the bonnet and the coolant was bubbling and in the end it emptied it self out on the floor. seems the fans didn't come on either ? also checked the oil and confirm all okay and no creamy colour in it. confirm no smoke from the exhaust either... could it simply be the thermostat, maybe the coolant top ?

 

or is this sounding like a head gasket job ? :(

 

cheers Matt

[robrado974 1]

It could be the thermostat , header tank pressure relief or simply that the sender for the fans is shot .

[Jon_vr6 1]

Could be the yellow sender on the thermostat housing too.

[mattyd6892 10]

thank you for that... :) where the best place for these parts ? .. will have to get it checked out first if its something simple like this.

[Keyo 47]

thank you for that... :) where the best place for these parts ? .. will have to get it checked out first if its something simple like this.

 

Have you checked if the plug is fitted in correctly at the back of the fan , they need to be pushed in really tight, also the bubbling at 110 sounds like air inside the system which might indicate that someone has had a hose off lately or changed the coolant , it should bleed by itself. Give the engine a run the fan should come on between 95 and a 100 and see if the fan comes on after you have given the main ffan plug a good push in, if it does then problem solved. The coolant should not escape at 110 so you have a weak hose or tank, however under 110 they might not leak as it's under less pressure, I know a lot of aftermarket hoses leak at 110 as not as well manufactured as Stock hoses.

Edited May 30, 2019 by Keyo

[Dox 23]

Is there pressure in the hoses when hot? There should be some to prevent the coolant boiling.

 

Water pumps are known for the impellers rotting off and not circulating the coolant.

 

Does it overheat when idling, driving, after you turn the engine off or all the above?

[fendervg 32]

Best place to stat is the "Definitve VR6 Cooling" thread:

http://the-corrado.net/showthread.php?38925-The-definitive-VR6-cooling-guide

and work your way through the various items - if there are no leaks from anywhere, check the stat, fans and sensors and make sure you use a proper coolant mix - and let the system bleed as it warms up by leaving the cap off and topping up before sealing it.

[mattyd6892 10]

thanks for that.. is there a certain process how to bleed these cars to check for air locks. wondered how you would do it on these unless the normal process

[mattyd6892 10]

Best place to stat is the "Definitve VR6 Cooling" thread:

http://the-corrado.net/showthread.php?38925-The-definitive-VR6-cooling-guide

and work your way through the various items - if there are no leaks from anywhere, check the stat, fans and sensors and make sure you use a proper coolant mix - and let the system bleed as it warms up by leaving the cap off and topping up before sealing it.

 

thanks for that.. is there a certain process how to bleed these cars to check for air locks. wondered how you would do it on these unless the normal process

[fendervg 32]

Fill up from cold, leave the cap off and start engine, then let it warm up and squeeze each coolant host in turn a few times as they fill up, you will see air bubbling out of the expansion tank.

 

When the thermostat opens the level will drop drastically as the radiator fills up, fill up again and check the hoses, give it a final top up to the correct level and drive for a while. Then let it cool and top up again - assuming no leaks and correct pressure it should then stay at that level when cold. Remember this is a fully sealed pressurised system to allow the coolant to heat up more, so under no circumstances remove the cap when the engine is hot, as you will have an explosion of high temp coolant in your face and all over your hands.

 

The above has always worked for me.

[mattyd6892 10]

thanks will give this a try.. will make sure its all bled out then .. also will check the plug at the back of fan as above advised sometimes they need a good push in too... all new to this car. are the plugs easy to see under the bonnet

[Tigerfish 10]

Where did the coolant come from when it emptied on the floor?

[1xshaunx1 27]

This explains how to check if your sensors are operating the fans. Just have to bridge a couple of plugs. http://the-corrado.net/showthread.php?38925-The-definitive-VR6-cooling-guide

[Keyo 47]

The large plug is connected to the back of the fan motor behind the radiator.

[fendervg 32]

There's also the radiator temperature sender/switch in the bottom corner of the rad, near the bottom inlet hose from the thermostat 0n the battery side.

[mattyd6892 10]

thanks for all the advice guys,, going to look at all this when home and report back back..

regarding the coolant on the floor, haven't driven it since incase so didnt look, but get it jacked up have a proper look today

[fla 9]

You can put a large piece of cardboard underneath the car and see where it lands. Also, check for any 'crusty' hoses where coolant and dripped and then dried up.

I flushed the system by opening the drain port under the crack pipe. I then just put a hose into the header tank and let it drain and flush until the water ran clear. I thne started the engine and continued flushing, and then refilled once everything was clean.

[mattyd6892 10]

so guys, spent some time on it tonight,, had a replaced coolant top as the old one was original and not as flush. Done a bled of system not much air really at all. car ran for about 25 mins and hit about 110 degrees and the fans havent come on at all. Going to do a fan test tomorrow to see if its working.. i guess this is bridging the plugs ? if the fans are okay i guess it could be a faulty thermostat. good thing is drives like a dream still and takes the head gasket out of this now ! also confirmed no leaks or anything ! everything looks solid !

[Keyo 47]

Yeah don't worry about the head gasket I think the lads with turbos they can go up to 120 , these blocks can take a bit of heat. Have you found the main plug yet that fits in the back of the fan, the same happened to me apart from coolant leaking, heard the bubbling from inside the cab and pulled over the plug was slightly dislodged. Start off with the easy stuff to illuminate.

 

Attached picture of plug also check the cabling is intact at the back of the plug.

 

[ATTACH=CONFIG]97101[/ATTACH]

Edited June 1, 2019 by Keyo

[mattyd6892 10]

yeah thanks mate.. reason why the coolant did what it did is was driving along and didnt relise and the temp so escaped in the end.. great will check this today . i did yesterday but double check again.... have you ever tested the fans before using the method to bridge the plugs ?

[Keyo 47]

Not myself I'm afraid.

 

It could be the fan switch as well which I have also circled.

 

[ATTACH=CONFIG]97102[/ATTACH]

[fla 9]

To check the rad sensor just bridge two of the three wires and the fan should come on. Cant remember which ones but theres only a few combinations and no electrical risk.

[_Matt_ 32]

Sounds like your fan controller might be dead. The soldered joints go crusty with age and fail. The VR6's have a 3 stage fan, controlled by multiple inputs from the coolent sensors and rad fan sensor. I can't fully remember it but it's in the guide -> readings from various sensors tell the fan controller which stage fan to run.

 

I had a problem with my rad fan sesnor and was only getting stage 2. Replacing it gave me all 3 stages.

 

These sensors are cheap - I would replace the yellow, blue and black sensors on the thermostat body and the Rad Fan switch on the rad and go from there. Also check the solder joints on the rad fan switch and re-solder as needed.

 

Yellow does the dash read out and controls stage 1 fans. Blue just sends a signal to the ECU for fuelling. Black I believe comes into play for stage 3. Rad Fan switch plays a part in stage 2 fans. But the key is they work together to complete the system so if one is duff it causes problems with the 3 stage fans.

 

Stage 1 fans can barely be heard. Stage 2 will come on for a few moments and can be heard. Stage 3 I've never heard but is apparently very loud!

Edited June 1, 2019 by pfnsht

[1xshaunx1 27]

I think the above is mostly correct but,

The sender/sensor in the rad does stages 1 and 2 that’s why it’s three pin. The yellow one has something to do with after run. It’s all in the guide which I have used to prove my older sender wasn’t working properly. If you bridge the plug from

Red to Red and White - stage 1 should come on

Red to Red and Black - stage 2 should come on

If you remove the plug from the fan and put a test light from the red and white wire to ground and bridge the

Red to Red and White on the rad sensor plug, the test light should light up. If it doesn’t there is something wrong with the controller as pfnsht says.

Below is a picture of the plug you need to remove and bridge. Your ignition needs to be on. When you turn the ignition on you should also here the electric secondary water pump come on for a bit. If you don’t here anything you need to investigate this too.

[Jon_vr6 1]

When my fans didn't work and the temperature kept rising and water bubbled it was the yellow sender on the thermostat housing. That was changed and fans came on as normal.