Overheating problems

[johnymd]

I thought I'd throw this out there for suggestions. Those people I've already asked, please don't feel offended that I'm still asking others. I do value your input but want to put it out to a wider audience and maybe help those with turbo hybrids that may find they have the same problem as me.


Anyway, the car has an ally rad and the core is exactly the size of the hole in the rad support panel. A large kenlow push fan is then mounted in the hole in the support panel. The intercooler is then in front of the panel and exactly cover the support panel hole with no gaps around the outside. The car has no oil cooler and the turbos are water cooled.

Under normal driving and in traffic it stays at the thermostat opening temp ans I only need the fan on if stationary after spirited driving. At normal motorway and high speed driving it's also OK. The track sessions at Mallory also showed no increase in temperature throughout the session. Now at Spa, at the end of the long uphill straight, on full throttle and boost it got hot and stayed hot for the next few turns. Only cooling down by backing off and coasting in 5th. This really messed up my fun and I need to find a solution for next year.

I'm guessing the turbos are producing a lot of heat which is being transferred into the water and also the heat from the intercooler isn't helping. I've no idea how hot intercoolers actually get so I don't know how much this could be contributing. I could do with an oil cooler but the only place for this is near the rad so this could actually make matters worst. I'd looked at tilting the intercooler forward to allow air to pass around it and through the rad but from what I've read this could make the airflow worst due to turbulence.

 

[Alphabettispaghetti]

Has hot air got anywhere to escape? to make an oil cooler work it has to be either far away from the radiator or mm from it, theory being that it keeps it in air flow and not in a high pressure
hot air pocket.

Oil cooler should produce an instant improvement for fast running.

 

[racer]

This seems to be a common conversion John, not sure why? perhaps higher volume?

Hydrofan Removal - Installing 2JZ Water Pump To 1JZ - *How to with pics*

 

[morbias]

Replace the pusher fan with a bigger volume puller maybe. Pusher fans are less efficient as the center of the fan where the motor is creates a big deadspot.

 

[johnymd]

Frankly - there are vents in the bonnet but this could be part of the issue. Good info on the oil cooler, I didn't know that.

Matt - I already have the 2jz type pump.

Morbias - I had considered changing the fan because of how much it blocks the rad. I don't think it has much effect over 30mph. Good suggestion.

 

[johnymd]

I wish I had tried running the bonnet on its latch to se if it improved under bonnet airflow. Not something I can test on the road.

 

[datsun dave]

I wish I had tried running the bonnet on its latch to se if it improved under bonnet airflow. Not something I can test on the road.

Vented bonnet or have the inspection flaps louvered ?.

 

[jonbills]

I think there's either too much hot water for the rad to handle, or the water's not getting through the rad fast enough. Monitoring the temp of the rad as well as the temp of the water in the engine would confirm which it is.
(assuming your temp sender is somewhere around the engine rather than in the rad!)

 

[johnymd]

Dave - Bonnet is from a 280z so vented. Although the vents aren't fitted. Standard inspection flaps so I could vent them, or remove for long circuits. Another thing I could off tried!!

John - could be.....probably. Looking for alternatives or the easiest way of curing the problem.

 

[jonbills]

I guess my point was that you've got to find out what the problem is first - if the rad is staying cool when your engine is overheating, then moving the kenlowe or intercooler etc won't help!

 

[johnymd]

Good point. Trouble is, I can't get it to overheat in normal or even hard use. So, I'm trying to make educated guesses without spending too much money.

 

[zbloke]

If the water was travelling through the rad to quickly wouldn't that make the overheating worse? the rad would not have time to cool the water sufficiently before it was returned to the engine?

John, I think you need to invest in a pack of self adhesive temp strips, stick em round the cooling system, run the car as hard as you can, perhaps on a rolling road that could simulate full load/boost conditions, and see what readings they give you

 

[SeanDezart]

Alloy rad !

What does that mean - it's like saying I've got a 6-2 exhaust manifold - there's loads of models !

Which rad have you ?

 

[johnymd]

Sean - well it's srt of squarish and made of Ali. Cross flow design, not running a header, the size of the hole in the support panel and made by griffin. Cost abou £100 from summit.

 

[SeanDezart]

Photo please. Keep you sarcasm this evening - I've had a bad day and don't want to be banned for any remarks.

 

[johnymd]

Oh go on Sean, I'll pretend it's just banter, you know you want to

I'll have a search for a pic but I'll have to admit, it is on the small size. I ordered it in a hurry and when it came I new it could have been taller. I don't really want to replace it as 99% of the time it's fine. I think I just need some minor tweaks. Maybe just a header tank to increase the quantity of water will do.

 

[SeanDezart]

I'm asking because all this blah, blah about bonnet vents and insp hatches is nice and allows a flow-through of air but DOESN'T address the source.

It sounds like the water is going through the rad too fast.

 

[racer]

John this seems to be the rad size required for a tuned Supra. How does it compare to yours?

WINNER ALLOY RADIATOR TOYOTA SUPRA MK3 JZA70 1JZ-GTE TWIN-TURBO 2.5 MT 1988-1993 | eBay

 

[Mr.G]

John, what your experiencing could be connected to you not having an oil cooler.

I know you don't just want to throw money at the car without being sure to solve the issue but the way i see it, fitting one is good standard engineering practice anyway and could solve what your experiencing.

 

[johnymd]

Sean - funny you should mention it but I was talking to someone at the z meet on Sunday about this and telling him that you needed to slow the flow down to extract more heat from the water. A deeper crossflow rad may be the answer.

Matt - proable not, but it works most of the time.
George - your right and I've got most of the parts to do it. Just don't have the time as I can't risk taking the car off the road and missing a meeting.