mikuni

Sheepers' RA28 Celica

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One more note, if you measure the radiator outlet temperature at idle, that'll tell you if the fans aren't keeping up or if the water flow isn't keeping up.

If the outlet temperature keeps climbing with engine temp, fit some bigger fans or bigger rad. I recommend a full shroud rather than sticking the fan directly to the rad like you currently have, as the fan is probably only utilizing half the radiators cooling area.
If the outlet temp isn't climbing at the rate of engine temp, you don't have enough coolant flow through the engine at idle for some reason. Also I just remembered the waterpump is cambelt driven, so fair to say that hasn't changed. Running a hi-flo thermostat?

Edit: perhaps your condenser is blocking / diverting air away from the rad too, try whipping up some channels to ensure the air has nowhere else to go.

Giving up solves nothing!

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1 hour ago, sheepers said:

Some further learnings.

Did 150ks in it on the motorway.  It will sit at 88deg with air flow,  climbs as soon as i slow down from 100.

 

IMO your radiator and fans are not up to the task. 

Did you try the hose on the radiator trick? 

Can you unbolt the ac radiator for now to see if that makes it better with more air flow directly on the radiator?

Does driving around with the heater on full hot make it better? 

I think you need to forget the fact that it used to be ok before fitting the blower otherwise you will continue to chase your tail looking for the problem

 

Xox good luck etc  

 

Edit, yowzer covered it 

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Does the car have the lower shield "bash guard" (it's not really a bash guard, but it goes where one would) the help create an area of low pressure behind the radiator to.encourage air through the radiator.

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43 minutes ago, cletus said:

IMO your radiator and fans are not up to the task. 

Did you try the hose on the radiator trick? 

Can you unbolt the ac radiator for now to see if that makes it better with more air flow directly on the radiator?

Does driving around with the heater on full hot make it better? 

I think you need to forget the fact that it used to be ok before fitting the blower otherwise you will continue to chase your tail looking for the problem

 

Xox good luck etc  

 

Edit, yowzer covered it 

Yea but, inlet temp under the blower is not high,  like it's the same as an NA motor. 

It gets hot and climbs at idle where the blower is doing nothing. 

I really fail to see how the blower,  which has a vac bypass, is contributing/ causing this. 

Ive run it with the belt off. It still does it. 

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On the off chance it's tune related do you think a tuning session on a dyno would potientally be beneficial? They can wack the big fans on which might keep things cool enough to get a tune done. 

Im unsure what fans your running but are there any factory maybe multi speed options you could use that flow more air and have a built in(on) shroud? 

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The crossover pipe at the back of the heads in the below photo, can you unplug that heater hose and confirm there’s water in there/put some water in there? It looks like an obvious place for and airlock - I mean, how does the air get out of there? Also Google says thats a common place for an airlock  and apparently it’s worse if you jack the front of the car up when filling the cooling system 

887B5E1D-BD7E-41B8-875F-40FED33DE962.jpeg.478c71778d9636f8b14c8db59d8f90a8.jpeg

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3 hours ago, sheepers said:

I really fail to see how the blower,  which has a vac bypass, is contributing/ causing this. 

Yeah I doubt it's blower related too. TBH I reckon you chuck on a giant two stage Volvo fan and carry on as per usual

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15 hours ago, Evan said:

The crossover pipe at the back of the heads..... It looks like an obvious place for and airlock.

I reckon this man might be on to something. Is it possible to force fill the rear hose or add a bleeder to the high point to test this? 

A vacuum filler as discussed earlier in this thread could be the ticket. 

 

Yowzer's diagnosis process seems logical also. 

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887B5E1D-BD7E-41B8-875F-40FED33DE962.jpeg.478c71778d9636f8b14c8db59d8f90a8.jpeg

 

Found your problem M9, you have no radiator in the cooling loop..

 

/totalLing

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G'day,

In the workshop we'd always be pretty pessimistic with a problem like this sorry. If not blown head gasket, then cracked block or cracked/warped heads. Can you check for combustion gases in the coolant? You'll need to remove the old coolant and refill to ensure an accurate test (Teekay test) Does it overpressurize quickly before warming up from a cold start? Do you see bubbles in the radiator when running up from a cold start? You can temporarily extend the filler cap neck with a funnel etc to check for bubbles when running up.

You can pressurise the cooling system 13psi and leave overnight and see if it hydraulics/coolant in the combustion chamber. Disable the fuel pump/crimp the line, spin it over after leaving pressurised overnight with the plugs out and check for coolant mist shooting out the plug holes. Coolant in the oil? Compression test? Often after you do a hot shutdown, you might hear/feel gurgling in the top radiator hose which is not a great sign.

edit added stuff/disclaimer: take this with a grain of salt, it is impossible to diagnose a cracked block over the internet.

Apologies/delete if this has been covered already.

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Ok. Here’s my silly suggestion. 
If its getting hot on the fans, are you sure they’re running the correct way?

 

 

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Some great oldschool wisdom so far here on a tough problem . my question/suggestion is water pump related , I have over the years encountered the following problems (on assorted makes/models) with new pumps ; impellers that are different diameters , different depths , vanes rotating opposite directions . Not always obvious at a glance and will usually circulate water just not very efficiently making diagnosis challenging ....... good luck , hopefully an easy fix is found soon allowing you more time to make the rest of us look bad with your next project !

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On 18/03/2020 at 17:36, sheepers said:

Yea but, inlet temp under the blower is not high,  like it's the same as an NA motor. 

It gets hot and climbs at idle where the blower is doing nothing. 

I really fail to see how the blower,  which has a vac bypass, is contributing/ causing this. 

Ive run it with the belt off. It still does it. 

 

At least the pressures off now.. 

 

 

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Hello Sheepers.

I'm finding your overheating issue irksome too. I have a car that does a similar thing. and it's very frustrating.

If vacuum bleeding it is making an improvement it makes me think there is an airlock somewhere. At a workshop I worked at in the past a car was brought in that had a V8 swap and it would overheat, all the usual had been done. We found that topping the cooling system up at the back of the manifold and a couple of other places around the cooling system made all the difference and solved the problem.

Could you do something like add a couple of ball valves one at the back heater hose and one at the air outlet behind the thermostat and try to force the air out with the garden hose then shut the valves and test drive it? Or make some type of basic header tank to give the air a high point to rise to?

My two cents anyway.

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yea, the "yay this vacuum bleeding might fix it" bubble has burst.

its better, but a trillion miles away from being a usable car.

 

im fucking over it, it can sit in the corner pissing me off every time i look at it for a while. in the mean time ill work on other cars. 

if/when i go back to it ill try adding water at the back of the motor somehow, or some fucking thing. but for now it can get fucked. 

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I came to the same point

I'll look forward to an update in a decade.

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