2JZ over heating problems help please??

[Py7h0n]

Isolate the system:

Loop the heater
Loop the Oil Cooler
Get the cooling system back to basics.
Get the radiator checked (rodded?) My first "aftermarket" was shite - Custom made one fixed all my problems because it actually flowed!
Check for corrosion in the water pipes and fittings (remove all fittings on block)

Get the water passeges in the head checked and cleaned while the head is off.

I had a overheating problem with mine - Ended up "Ovaling" my Aries pistons from a single "to the red" overheat.

Best thing with a cooling system is keep it simple - The less parts, fittings, joins, pipes, the less to go wrong!

[Py7h0n]

Just re-read and saw you have a link.

Have you confirmed and triple checked that the ignition timing edge is set correctly on the ECU. If set wrong you will have no end of overheating issues.

Also make sure that the static timing (on the crank) matches what the ECU says with a timing light - WAY too many 'Tuners' overlook this simple step.

[trd-drifting]

Cheers static timing and with the timing light is correct tripple checked that i remember, When i have all back together and start i will check what the link says as i do not think i have checked that, be a few weeks knowing me.

Isolate the system:

Loop the heater
Loop the Oil Cooler
Get the cooling system back to basics.
Get the radiator checked (rodded?) My first "aftermarket" was shite - Custom made one fixed all my problems because it actually flowed!
Check for corrosion in the water pipes and fittings (remove all fittings on block)

Get the water passeges in the head checked and cleaned while the head is off.

When you say loop the heater you mean just bypass the heater core in the car? I have done this and also put a bleed valve in the top as it was the highest point in the cooling system.

What do you mean by loop the oil cooler?? as do not run the factory lines to the factory oil cooler as that is all i have at this stage?

Then just remove all frost plugs and clean out? this is all i can really do correct?

The head has been checked in that regard as i just rang and asked, last time it was off when it was machined etc.. and crack tested but can do it again. As this motor came from Osaka with a BHG and they didnt want to know about it.

[Py7h0n]

frost plugs if you suspect it but I would be happy with the water fittings.

If you are worried about the bottom end - Pull it, tank it and rebuild it. Bearings and rings, etc a lot cheaper piece of mind.

I would check the ignition timing edge coming the the ECU with a meter - If rising / falling is wrong (software glitches happen) then that could be your problem.

[allencr]

...a kinked heater hose line which i do not think is the root cause of the problem but defintly is adding to it. Cannot believe i did not see this in the car. water still runs through it but just.

Looks like a heat exchanger, oil to water, and it shouldn't have done anything except keep you oil from warming up along with the coolant while the thermostat is closed & keeping oil temp down when under a heavy load/thrashing. If it was contributing to your problem in any way, it wouldn't be more then 1-2 degrees worth IMO.
If it's not a BHG & not an impeller less waterpump & not a clogged radiator internal/external & not an air flow problem & not an engine swap hose routing problem like trying to draw from the radiators upper into the engine, then I don't have a clue. Sorry. Good luck.
***
****
Also, sure it's not a gauge problem?

[matt dunn]

FWIW those water cooled oil coolers do amke a big difference.

With a 2JZGTE enduro car we ran, they changed oil brands to one that did not absorb the heat from the engine into the oil as well as the old stuff,
and the car would overheat in a 1o min qualifying session.

Changed the oil back to what they used to run and then the car ran a 3Hr race without overheating,

so that oil cooler must have an effect.

[Crucible]

If it's not a BHG & not an impeller less waterpump & not a clogged radiator internal/external & not an air flow problem & not an engine swap hose routing problem like trying to draw from the radiators upper into the engine, then I don't have a clue. Sorry. Good luck.
***
****
Also, sure it's not a gauge problem?

I agree, overheating faults are not hard to rectify. This is how I go about every overheating fault that comes into work.

1 - TK - Chemical check
2 - Pressure test system

If both these checks are fine you have a flow problem.

3 - Thermostat
4 - Remove radiator and rod
5 - Water Pump (Corroded or detached Impeller)

Just make sure you have no airlocks in the system when topping up coolant, if it keeps boiling over let it cool down and just keep topping it up. Thats all there is too it. Dont get too technical and overthink things, cooling systems are very basic.

[trd-drifting]

I agree, overheating faults are not hard to rectify. This is how I go about every overheating fault that comes into work.

1 - TK - Chemical check
2 - Pressure test system

If both these checks are fine you have a flow problem.

3 - Thermostat
4 - Remove radiator and rod
5 - Water Pump (Corroded or detached Impeller)

Just make sure you have no airlocks in the system when topping up coolant, if it keeps boiling over let it cool down and just keep topping it up. Thats all there is too it. Dont get too technical and overthink things, cooling systems are very basic.

I agree completly but got stumped last year before i wrote the car off, thought i had exhausted most avenues or just missed somthing simple. I have been rather busy and im in the process of shifting house at the moment, but will go through everything evryone has mentioned, again but most of these things cant be done till i put the head back on the motor. Will post back on here when i have it in my new shell and running if i still cant find any problems. At least i know it will have to be somthing external when i put the head back on.

Cheers heaps for all the responces very much appreciated thankyou guys.

[MAGN1T]

Pressure tests don't work, like lots of other tests.

The pressure test that's normally done is to pump up the cooling system to 15 or 20 PSI and watch it bleed down (or not bleed down).

Don't you think that's a bit pointless when cylinder pressure is in the order of 1000PSI when the sparkplug fires?
So that's 1/50 the required pressure AND in the wrong direction.
The only pressure test that actually works is to fit a pressure gauge to the cooling system and take it for a thrash, watching that the gauge never exceeds the rating on the pressure cap.
That's the only 100% effective test for a headgasket leak.
As for TK tests, they're a waste of money too. Just for mechanics who don't know WTF they're doing.

Steve

[Mr Ree]

A pressure test if for finding obvious leaks though, so 15-20psi is enough to build pressure and see it trickle out of a pin hole leak in a water hose.

They work, thats why they are used by lots of mechanics.

[Crucible]

Pressure tests don't work, like lots of other tests.

The pressure test that's normally done is to pump up the cooling system to 15 or 20 PSI and watch it bleed down (or not bleed down).

Don't you think that's a bit pointless when cylinder pressure is in the order of 1000PSI when the sparkplug fires?
So that's 1/50 the required pressure AND in the wrong direction.
The only pressure test that actually works is to fit a pressure gauge to the cooling system and take it for a thrash, watching that the gauge never exceeds the rating on the pressure cap.
That's the only 100% effective test for a headgasket leak.
As for TK tests, they're a waste of money too. Just for mechanics who don't know WTF they're doing.

Steve

OMG!!STFU! you have no idea! I have 19 years in the trade and have Trade certificate and National certificate in automotive engineering.

You cant have any mechanical experiance what so ever as it truley shines through your posts. Ive lost count the amount of times you have put people wrong so do everyone a favour and stop posting worthless dribble on this furum! TWAT!!!

[Gadget]

Also what rpm does standard 2JZ turbos kick in as it seems a lot laggier than my 1JZ. I have removed all the little valves and solonoids and the butterfly valve in the intercooler piping so both turbos spool at the same time. Full boost (12psi) took till 3600rpm according to the dyno charts and im sure my 1jz was like 2800rpm.

One of my Supras had this done. From memory there's a butterfly in the exhaust downstream of the front turbo too?

That said, I experienced exactly the same behavior in 'true twin' configuration - it gave no discernable benefit, and meant boost <3krpm was almost non-existant. I ended up putting it back to sequential, much nicer to drive and no difference in the top end... (dyno'd at 260rwkw just with exhaust - std ecu, fuel, induction etc).

Cheers,
Ben.

[MAGN1T]

Pressure tests don't work, like lots of other tests.

The pressure test that's normally done is to pump up the cooling system to 15 or 20 PSI and watch it bleed down (or not bleed down).

Don't you think that's a bit pointless when cylinder pressure is in the order of 1000PSI when the sparkplug fires?
So that's 1/50 the required pressure AND in the wrong direction.
The only pressure test that actually works is to fit a pressure gauge to the cooling system and take it for a thrash, watching that the gauge never exceeds the rating on the pressure cap.
That's the only 100% effective test for a headgasket leak.
As for TK tests, they're a waste of money too. Just for mechanics who don't know WTF they're doing.

Steve

OMG!!STFU! you have no idea! I have 19 years in the trade and have Trade certificate and National certificate in automotive engineering.

You cant have any mechanical experiance what so ever as it truley shines through your posts. Ive lost count the amount of times you have put people wrong so do everyone a favour and stop posting worthless dribble on this furum! TWAT!!!

OK so what you're saying is that pressurising the cooling system to maybe 20 PSI is a perfectlty good way of finding a leak in a headgasket which only occurs when cylinder pressure exceeds 1000PSI?

Is that right?

19 years in the trade?
19 years ago my daily driver had a turbocharged 351 Cleveland in it, rajay turbo, Weber 45DCOE and CNG which I built 100% myself.
When I stepped on the loud pedal the cooling system pressurised every time. Easy fix, just carry lots of water in the back.

Steve

[rollaholic]

jesus.

pressure tester and TK tester both have their uses. they are tools, just like a spanner, or your brain. if you use it in the wrong way, then of course its going to seem pointless.

[Mr Revhead]

jesus.

pressure tester and TK tester both have their uses. they are tools, just like a spanner, or your brain. if you use it in the wrong way, then of course its going to seem pointless.

ahhhh.....

[rollaholic]

jesus.

pressure tester and TK tester both have their uses. they are tools, just like a spanner, or your brain. if you use it in the wrong way, then of course its going to seem pointless.

ahhhh.....

hint - its not a hammer

[rollaholic]

The only pressure test that actually works is to fit a pressure gauge to the cooling system and take it for a thrash, watching that the gauge never exceeds the rating on the pressure cap.

maybe this is why you think every car in the world has a BHG?

[matt dunn]

How would the pressure exceed cap pressure,
when the cap releases off anything above cap pressure?

Not going to get 20psi in a system with a 15psi cap unless the cap dont work.

[MAGN1T]

It's no different from a wastegate valve or a fuel pressure regulator or electricity (V=IR). There's a relationship between pressure and flow.
With your fuel system, fit too big a pump and it will usually ourflow the regulator and you'll have too much pressure at idle.
With a radiator cap rated at say .8 bar, it'll crack open at .8 bar but if it can't vent all the gas then the pressure rises and hoses pop, radiator pops and heater core pops, all of which have happened to me way back.
Of course fitting a higher pressure cap is pretty common as is fitting an aluminium radiator, neither of which are very clever ideas.

Got told by a "pro" haha recently that the plastic filler tanks on soobys are crap because they split due to the heat, they split due to too much pressure when the HG leaks, NOT due to getting too hot. But you get that.
Of course when the rad cap cracks open and vents, it's only a matter of time before the seal splits and leaks all the time, that's the "effect" not the cause.
The difference between trained professionals and hotrodders is that with hotrodders the problems (customers) don't go away.
They get fixed. Properly.

Surely everyone has seen split radiator top tanks?
How many PSI does it take to cause that?

Steve

[Dell'Orto]

Very little when the plastic breaks down - why is it the top tank is always the one that splits and never the bottom?