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The fans are for the aircon and only come if needed at the last moment to assist the cooling of the engine. Normally when it's too late.....
P38 oveheating
- Thread starter Wayne890
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Toyota Twonk
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So when the airlock is pushed out does it stay cool?
So it’s passed the news paper test and I thought I’d have another go at blessing air out of the system. This has been going on for months now I have bleed it a lot of times I know what it usually looks like. This morning as well as a lot of air I have been getting a white foam from the breather pipe at the top of the expansion tank. It this foam indicative if another problem or has putting another rad on released an air lock and this is coming out now? Obviously white foam isn’t known for its cooling properties. I had it running with the cap off for over an hour didn’t over heat. I’ll go back to it once it’s cooled down and have another look.
This hasn’t happened before coolant in the tank is collect once the bubbles pop. I topped the oil up as well oil looks fine
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If there's air in the water pump then that can foam a bit as it gets agitated
If it's thick sludgy foam them that's not right. Have you got a pic of it?
If it's thick sludgy foam them that's not right. Have you got a pic of it?
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The bleed pipe from the top of the rad to the expansion bottle neck, you need to disconnect from the radiator and blow down it to make sure it's clear as that can airlock. Only reconnect it with the expansion cap off and when the expansion bottle is full so there is coolant coming from the rad connection.
Datatek
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The electric fans are for the aircon, nothing to do with engine cooling but as I said the aircon condenser radiator on front of the engine coolant RAD can become blocked stopping airflow.
I don’t have a picture but it’s not think and sludgy. It’s a very fine pure white really fine disappears almost as it hits the air. It’s like the foam you get in kids bubble mixture
Datatek
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It's easier to get the air out of the block with the front of the car raised a bit. Rapidly squeezing and releasing the top hose with engine idling and cap off will also help.
So I think I got all of the air out and the white foam stopped coming out. My mechanic tells me that he got all the air out when he changed the rad. After a longish drive yesterday the system had lots of air in it again. The system is not leaking and it is pressurised. Where could this air be coming from it’s got to be something simple. We have done every possible test to detect a problem with the head gasket and it’s passed every one. It’s been doing this since January so I doubt the head is the cause of the overheating. It’s absolutely fine driving around town and sitting in traffic. It’s fine at speed. The problem now seems to be when you stop after a long drive and the air is not flowing over the engine any longer. It’s a mystery where the air is coming from though.
Datatek
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Have you done a sniff test on the coolant to check for exhaust gasses?
I'm sorry to say that the problem is beginning to sound like a cracked cylinder head, the one I scrapped had very similar symptoms.
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Silly question but did you do the right one? There's different tests for petrol and diesel
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Did the thermostat go in with the pip at the 12 o'clock position?
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Were the coolant pipes put back right when yhe heater matrix was changed?
Sure there isn't sealant of something blocking a passage in the coolant ways?
If you get it hot, carefully release the pressure at the expansion tank and then retighten the cap does it build up pressure again?
You can use the glow-plug holes to push pressurised air in and see if water comes out of the expansion cap. If it does then either head-gasket gone or more likely a cracked head.
Sure there isn't sealant of something blocking a passage in the coolant ways?
If you get it hot, carefully release the pressure at the expansion tank and then retighten the cap does it build up pressure again?
You can use the glow-plug holes to push pressurised air in and see if water comes out of the expansion cap. If it does then either head-gasket gone or more likely a cracked head.
Datatek
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Never assume garage mechs will get it right
So back on this again. I intended to rig the air con fans infront if the radiator to be on all the time to see if this helped with over heating. Turns out the passenger side fan doesn’t work even when connected directly to the battery so I have got the other fan to come on with the ignition. Does anyone have any experience or knowledge with these fans? What they should do when they should come on etc?
