mikuni

Sheepers' RA28 Celica

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Form that it sounds like a fan flow or rad size issue then?

How hot are you letting it get when sitting? on some horrible inefficient thing like the buick 455 with a 90 degree thermostat it would always sit on that temp while moving. Even with the monster mechanical fan and new rad it would climb to 100-115 when sitting still, just part of life with a big hot donk (the thing was rebuilt so new everything). Could sit for 30-40min on a hot day in traffic like that before I would chicken out, unnerving watching something go over 100 that but its within spec with a pressurised (old shitty) system. I put massive (spendy good ones) electric fans, made a shroud and a controller thinking I could keep it down more in traffic but they were way worse, on all the time and climbing temps way faster. Moral of that shit yarn is the rad size is bordline for the heat output of that motor and the fan air flow made a huge difference.

probably not really helpful here, but maybe you maxed out your rad/fans? seems like with just the blower though you wouldn't have pushed the cooling system over the edge that much and it seems weird it goes nuclear in a minute.

Edit: Looking again at the pics closely and IMO the rad looks pretty small and fan setup sub-optimal?

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Might be time to start making a list of things we know it isnt. We can cross thermostat off as even with it out it made no difference. Radiators been tested and was the same rad as before you had problems. Not the fans as you  also had these before and they were fine.

Next start looking again at possible options. 

Is the waterpump still good? Not worn out and not flowing enough. 

Double check plumbing routing. 

Wrong head gaskets? Could they be from a different version of the motor? 

Water passages blocked up? 

A crack somewhere allowing pressure into cooling system? 

Supercharger not blocking coolant passages or something silly like that? 

Might be time to start pulling things down to investigate further? Not knowledgeable on this motor, take or ignore what I have said as you see fit as I could have missed previous discussions etc. I can understand the frustration but keep at it and when its finally sorted you will appreciate the car even more. 

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16 minutes ago, cletus said:

Maybe it was at 95% before and you never had a problem but now theres just enough stuff on it to tip it over the edge where it cant deal with it  

Yup this is where I was going with my ramble. It now has hotter intake air and more load it idle which could tip it over the edge, especially now its diagnosed as sitting on the thermostat while moving, that points to not enough air flow and/or radiator. The hose diagnosis is a good one, will narrow it down real quick.

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is the radiator and water direction plumbed correctly? as in hot water going into the bottom and cold coming out the top? cause it looks like its backwards compared to my engines. 

thermostat housing on all my engines goes to the top of the rad, and the waterpump outlet, goes to the bottom. 

edit,

i see its been mentioned a few times, but no answer on this one? quick google of an sc400 and it seems to be plumbed correct. adding the blower to the system hasnt acceidentally reversed the water pump pully or perhaps you've changed the crank pulley to effect boost and upset the speed of the pump?

Image result for 1uz engine

 

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11 minutes ago, BlownCorona said:

is the radiator and water direction plumbed correctly? as in hot water going into the bottom and cold coming out the top? cause it looks like its backwards compared to my engines. 

thermostat housing on all my engines goes to the top of the rad, and the waterpump outlet, goes to the bottom. 

 

Modern Toyota lyfe.. Thermostat controls water coming out of the radiator. 

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1 hour ago, BlownCorona said:

as in hot water going into the bottom and cold coming out the top

Hold up there, isn't that back to front to how it actually works?

Hot water Rises / goes iton the Rad @ top?

& cold water drawn from the bottom into the system

or am I completely wrong / I am still here to learn :P

edit : I googled a pic

Water_Cooling_4.jpg

Sauce https://www.uniquecarsandparts.com.au/how_it_works_radiator

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Can you check the head gasket sides are right with the end tabs sticking out between the head and block?

 

 

61AABF70-544F-4361-B946-CED91C477F41.jpeg

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lots of stuff to think about there, thanks team.

some points to note,

the engine gets hot without the supercharger turning at all.

the car never even came close to having cooling issues with the old motor, it would do skids, trackdays, sit in traffic with the air con running constantly and the needle never moved.

ill try the hose on the radiator trick tomorrow, although im not entirely sure what that will tell me. ive run the motor with the garden hose plumbed directly into the cooling circuit running a "total loss" water system and surprisingly enough it didn't get hot, but why would it, it had a constant flow of cold water.

and if it will drive, ill try driving it without the supercharger turning and see what happens.

 

i would have no problem taking the motor apart to replace headgaskets or whatever if i KNEW that was the problem. but taking the whole thing apart just to find theres nothing out of place would really suck big hairy donkey balls. 

 

general points so far,

ive put two different water pumps with slightly different impellers in it, no difference

tested two thermostats and both behaved the same, run the car with both, no difference 

radiator is clear and plumbed exactly the same as it was

i have a photo showing the markings on the head gaskets are installed the correct way.

the modifications to the water bridges are the removal of one 6mm dia water feed to the throttle body and plugging two sensor holes

there are two separate water temp gauge senders, one for the dash which is plumbed into the rear water bridge and one for the computer which is in the front water bridge and they correlate fairly closely.  

 

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Have you confirmed temp sensor is good? Seen it asked a few times so I suspect the answer is yes.

This is probably the greats thread on OS right now. Such suspense!

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Could it be your fans not pulling enough air somehow.. But it def seems like a flow issue. I fucken hate cooling issues.. Had it with my fairmont in melbs exactly like your symptoms now. Also had it with my hilux but I sorted that finally.. 

It there any way you could mount a viscous hub in there or is there not enough room? They pull a shit tonne of air. 

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Is it possible to put the old intake system back on for a test?

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Was that TB water feed also a bit of a bypass/air bubble bleed that you have removed? Could you try reinstall it bypassing the tb?

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My 2c.

Could it not just be that the newly rebuilt engine is running a bit hot as it breaks in. Have you managed to do a proper break in drive at different rpms and loads? Is the tune good enough for you to do so? Can you leave the fans on and go for a hoon? How hot is the coolant actually getting?

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9 hours ago, yetchh said:

It there any way you could mount a viscous hub in there or is there not enough room? They pull a shit tonne of air. 

They also pull a shit tonne of horsepower out of the motor..

I gained 9-10hp on the dyno just removing the viscous fan on my celica.

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Stationary full load cooling test, release the heat via the rear tyres?

Sorry nothing useful to add, but wished to say I have been following with interest and looking forward to a solution being found

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2 hours ago, sleeektoy said:

They also pull a shit tonne of horsepower out of the motor..

I gained 9-10hp on the dyno just removing the viscous fan on my celica.

 

That indicates to me that your hub was somehow fucked, when no cooling is required they should run freely creating almost no drag whatsoever.. Plus, this is a supercharged v8.. 

 

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Have you considered moving your injectors way further from the intake port, give you more chance to cool the air down? (I realise you say it still has the issues when supercharger isn't turning, so idk)

I was watching a video by haltech the other day and they reckoned with supercharged V8 stuff it makes a huge difference as they are supposedly one of the hardest configurations to get running properly without heat issues.

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if you really get stuck and want to talk to another person with a blown lexus v8 i can probably get you in contact with jase brown.

image-asset.jpeg

he done the swap below a long time ago.

255623_216311791734042_263680_n.jpg?_nc_

feel your pain at the moment and this is as helpful as i can get with in this situation 

he is extremely helpful with no mater what and is a super nice dude so i can only imagine he would want to help and just talk.

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I've been following this build with much interest. So much skill shown.

The only thing I can think of that may be of use in this instance, but you've probably tried it already, is to run it with the heater on full and see if that makes any measurable difference. If it does, even if it is a small difference, might that support the theory advanced by others that the capacity of the radiator is insufficient for the additional heat created by the supercharger?

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