help needed: 1jz coolant flow question

[Disturbed1]

this motor is in a track car which has gone single turbo and kept as simple as possible... as such the metal tube that runs right around the motor has been removed, therefore ive got all these ports exposed and i dont know if the flow is comming or going. what can i block off and what ports must i have hoocked up so that the colant flows through the head properly

cheers

[JZA70 R]

This is for a 2JZ-GTE but i will assume there are a lot of similarities...






If you still had everything hooked up, it would be quite simple to work out which direction coolant is flowing in each line just by tracing where they start and where they stop.

Perhaps find some photos and put the puzzle together, shouldnt be too hard to work out.

Todd

[Disturbed1]

pretty much know how it goes - all 3 ports on the plenum side are outlets
red = tb
blue = oil cooler
yellow = heater
core

all 3 of those combine then return to the the orange por

no idea hwat the purple one is for though - guessing turbos

[1JZ-Rolla]

Yes, purple one is one of the returns from the twin turbos. the other one went back to the stainless pipe that you removed around the back of the motor.

The two fittings at the top right of your last photo are the two water FEEDS for the turbo also, assuming you'll block one of these also?

[Disturbed1]

so will coolan\t flow through the head properly if i block off the orange one and the 3 on the plenum side?

[1JZ-Rolla]

The red and yellow ones you've marked on the plenum side are blocked on mine, but i'm not so sure of the effect of getting rid of the coolant passage that runs from the blue outlet, through the oil "cooler" and around the back to the orange marker on the back of the pump.... would need a more comprehensive diagram showing the coolant path inside the motor to work that out, not just the external pipework.

[ATMO_BT1]

Hey guys I am dealing with a similar situation right now and thought I would bump this old thread rather than starting my own

Disturbed1 did you end up finishing this build? If so would you mind running me through what you ended up doing with these coolant ports? And also what you did with the port on the exhaust side of the head where the big metal hard line begins (circled in orange)?

If so, did you end up suffering cooling issues?

I am in the same situation, race only engine with no a/c, oil filter housing, heater box and with a single turbo setup. I am looking for the simplest cooling system possible that deletes the hard line which runs directly under the exhaust manifold although am wary of creating hot spots by simply blocking things off. Also I am worried that blocking things off might cause the coolant to speed up to the point where it rushes past some small cooling channels in the head.

The other option would be to weld AN fittings onto the orange, red, blue and yellow outlets and then run a single braided line around the front of the engine past the timing case from the orange to the yellow with lines T-pieced off to the red and blue points. I feel like this would retain the same coolant circulation as OEM as well as similar capacity although without having to have the line run under the super-hot exhaust manifold. An additional line could even be t-pieced off the line and to a header tank to eliminate the chance of air pockets forming?

Ideally however I would love to just block everything up, which is why I'm really hoping Disturbed1 ended up finishing this and can let us know how it went!

[BrianRA23]

I am not sure how this engine was setup in the end, but the pipes leaving the back of the water pump housing to go into the engine allow for some coolant recirculation when the thermostat is closed. If you block them off then potentially nothing can flow when the thermostat is not open.

Manufactures realised the need for the recirculation since isolated boiling was occurring inside the head where there was insufficient coolant flow while the engine waited for the thermostat to get hot enough to allow flow through. The pipes exist to allow the engine to have (more) even temps.

Apparently the old Holden 5L engine alway did the head gasket on the cylinder next to the glove box since it was the last one to get cooled, when the thermostat was busy maintaining a good engine temp.

[e30-323ti]

I'm in a similar situation and found this similar thread on MKIVSupra.net which may be on interest.

LINK

The jist seems to be, just block them all off, the engines internal cooling passages are all the 'engine' needs, the other 'ancillaries' (throttle body, ISCV, Oil Cooler(/warmer), cabin heater) serviced by those ports and external pipe are secondary to the engines needs.
NB. That is NOT my first hand experience, just my summary/understanding of the linked thread above.

Be interested to hear anyone from heres first person accounts

[BrianRA23]

For race setup I would be more inclined to disconnect the heater and run the hoses into a header tank. This is because the port out the top of the head makes it the highest place to allow steam from localised boiling to escape. Once it is in the header tank (positioned above the engine) the steam can condense and continue circulating. Steam left inside the head is unable to absorb any heat and may result in distortion and cracking if the location temperature continues to rise. Your radiator cap can then be relocated to the header tank to make coolant filling easier.

I have noticed that there is no heater tap on the IS200 or the Aristo JZS161 so I suspect water is intentionally run through these lines all the time the engine is running, bypassing the thermostat. The core would be covered by flaps to prevent the ventilation system air going through the core.

[lexsmaz]

I'm not into blocking up water galleries that were there, i would personally run the metal pipes still & the heater, will certainly help on cold days if you are getting fogging up inside the car on the track ..

But if you still want to remove the metal pipes you could probably block some of them up, certainly the ones that go to the heater core, as Brian mentioned the heater tap completely shuts off the water supply through the core & hence the pipes so there is no water flow until you actually turn on the heater tap & you usually only do that in cold weather not hot so the heater pipes are certainly not helping to relieve any hot spot / coolant flow issues ..

[BrianRA23]

as Brian mentioned the heater tap completely shuts off the water supply through the core & hence the pipes so there is no water flow until you actually turn on the heater tap & you usually only do that in cold weather not hot so the heater pipes are certainly not helping to relieve any hot spot / coolant flow issues ..

What I meant is - there is no tap on the mentioned cars and therefore water always flows through the heater line and port in the head for those engines (2JZGTE vvt and 1GGE vvt).

[lexsmaz]

Hi Brian, i realised what you were initially saying & i probably should have not used your words as a reference, but what you said made me then remember is that on the 1JZ motors is that they have a heater tap & so as i said they then completely block off the water flow & so as mentioned i feel blocking them off would be quite ok ..

[e30-323ti]

I like the idea of running a header tank/cap off the heater port for aiding filling and more so collecting and steam directly from potential hotspots in the head.

I already have a swirl / header tank off the outlet before the (cross flow) radiator and was keen to retain, and don't really like the idea of 2 pressure caps.

If we are happy capping the heater outlet from the head, the only other thing that external tubing serves is the stock oil cooler and the rear turbo.
Neither are a real concern on a dedicated track car (with a single turbo).

[ATMO_BT1]

thanks all for taking the time to reply

it sounds like then if I were to delete the thermostat (which I am happy to do, having had track engines in the past without them), then there would be no need for recirc and that I could block off all of the lines on the intake side (throttle body, oil cooler and heater), as well as blocking off where the hardline comes out of the back of the water pump. This last bit seems drastic but would you guys agree that without a thermostat it would no longer be required?

Instead of welding all of these outlets off, if i choose to delete all of them I think I may weld -AN male threads to them instead and then cap them off so that if once the car is running it suffers terrible cooling, bleeding or hot spot issues relating to the ports being blocked off then I can reverse the process

if we could keep this discussion going that would be great

I actually had a chat to a friend who drifts JZ engines competitively in the heat of Thailand and over there it is commonplace to tap a -AN fitting to the back of the head and run the outlet of the water pump (where the hard line normally is), straight into it like this:





I'm not sure what they do with the inlet side though, assuming it's all blocked off?