Hello,
This is my first post on this forum. I have been here a bit though ever since purchasing our van a year a go.
Its a 1988 4wd Auto Tarago (thats what they are called here in Australia).
I know there have been lots of threads here addressing overheating. However, I have read most of them and performed all the recommended cures without avail. Any advice would be really appreciated. I'll lay out the details.
Issue: Overheating. Specifically under load at low speeds. Eg: labouring the engine up a steep hill with A/C on. No overheating on the freeway or at idle or if its a cool day. When I say overheating I mean the temp gauge going over half way into the 3/4 region. It definitely tends to overheat more readily when its hot outside. Its summer here so that doesn't help!
Background: I have had the van for 1 year. I love it- it does everything I want all in one car. It has never had overheating problems until recently. And I have worked it hard since having it: towing, carting heavy batteries, paddock work, etc. The problem first became evident when I was towing a trailer with some sheep to a customer (I live on a farm). It was a warm day with the ambient temp about 30 degrees celcius, I was towing approx 800kg combined weight and had the family in the car (wife and 4 children). The temperature gauge was hovering just over halfway for the outgoing trip but on the way home, when the trailer was empty, it climbed up close to the red as I slowed down from the freeway and came back into town. It never went into the red. I pulled over and the coolant boiled over. Ended up letting it cool down and refilling with water to get home. No issues getting home later that night when it was cooler. Since then it has had a tendency to overheat when the conditions are right.
What I have done:
- Replaced thermostat with a Tridon brand (from local auto store). Checked that it opens.
- Checked water pump. It is only 2 years old and spins freely and does not leak.
- Flushed and refilled coolant multiple times. The van has not really used any significant quantity of coolant during all this. Maybe 1/2 cup every 500kms or so. I find it hard to check as it seems to move in and out of the overflow bottle.
- Cleaned out radiator both inside and outside. It was clean and did not leak. Outside was grotty with grass seeds and dead locusts but is good now.
- Checked the thermofan. I wasn't sure it was working as it should so purchased a new clutch. It performed exactly the same as my old clutch (aisin) so I put the old one back in. I can kind of hear it blowing when I open the throttle at idle but I'm not totally convinced about it. I used to have a Volvo 240 and I could hear that fan come on and off really clearly from the cabin.
- I did a compression check thinking it must be a blown head gasket. 3 cyl were reading 160 psi and the 4th was 120 psi. I concluded it must be a blown head gasket causing all the trouble. I changed the headgasket and got the injectors cleaned as well. The engine runs well and the car has power but it still overheats!
- Checked Ohms resistance at the temperature sensor. It was not reading anything across the two pins and the workshop manual says it should be. However, the temperature gauge on the dash appears to be working. As in, its readings are consistent with the driving conditions and the times when it overheats. So not sure what to make of that...
I feel like I have done everything I can think of and everything recommended here by you all. I am at a bit of a loss. Any advice would be great.
I am inclined to think it is the thermostat. That is what it feels like when I am driving. It feels like maybe it should be opening earlier than it is or more completely open. It does not appear to open at all when starting the car and letting it idle. That is, the bottom radiator hose stays cold. Even when the engine is hot after a hill and I pull over and check things, the bottom hose is still never as hot as the top one.
Anyway, let me know what you think.
Many thanks in advance.
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Originally Posted by petedemol
