Hi from South Afrika
07-31-2018, 09:40 AM
Post: #1
Hi from South Afrika
Good day everyone. My name is Wessel AKA Witkind. I'm from Johannesburg South Africa. I don't have a Toyota as such, But I do have A 4 AGZE fitted In a project car, and have some questions on the cooling system. Especially on the water outlet at the back of the 16v head.

So here goes... Is it possible to completely blank off the water outlet, or do I have to run a pipe to the thermostat housing??
Will blanking off the outlet lead to any hot spots around the no 4 cylinder, and how does blanking it off differ from having it connected to a heater radiator but still having the selector in the closed position???

My apologies for posting my question here, I could not post in the normal Technical treat...

Thanks in advance, hope to hear from you soon.
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08-02-2018, 09:32 PM
Post: #2
Hi from South Afrika
Welcome! Wave
You have a very Dutch first name, are you from Dutch decent by any chance? Dumb question
I'll move the topic to the appropriate section. Wink

About the water outlet at the back of the head: as you can see in these schematics the Y at the back leads to both the heater and serves as a return line for the back of the engine:
[Image: AEU86 AE86 - Hi from South Afrika]
Water will still flow from the back if you block off the back outlet, but it will take longer a longer trip of the water to reach the radiator as it has to flow back through the entire head. This means the water should get hotter than if it would flow back via the back outlet. I don't have any experience myself with blocking this off, so maybe someone like oldeskewltoy could shed a light on it?

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08-04-2018, 10:08 AM
Post: #3
Hi from South Afrika
(07-31-2018 09:40 AM)Witkind Wrote:  Is it possible to completely blank off the water outlet, or do I have to
run a pipe to the thermostat housing?? Will blanking off the outlet lead
to any hot spots around the no 4 cylinder, and how does blanking it off
differ from having it connected to a heater radiator but still having the
selector in the closed position???

I'm inclined to think that having an outlet at the rear of the head has
more to do with packaging than with cooling performance. Having an
outlet at the back of a north-south engine, is convenient for supplying
water to the heater and provides a safe spot for mounting the engine
temperature sensor.

Cooling water distribution from the block to the head is primarily set
by the size and placement of the water holes in the head, block and
gasket. And as you mention, the cooling system must be capable of
doing it's job with the heater tap closed. This leaves only the small
tube connected to the AAV flowing any coolant from the rear of the
head, and that is tiny compared to the flow out of the front outlet.

So while I haven't tried blanking the rear outlet (RWD car), I can't see
that it would be a problem. You only need to find a new location for
the sensor/s. I think USDM versions have the ECU temperature sensor
in the front water neck. And you don't have a heater Smile

NB: Above applicable if you are coverting to a RWD water pipe setup
which has an internal bypsss on the water pump to flow water while
the thermostat is closed.

If you are using the FWD setup, the standard pipework includes a bypass
that sends water to the thermostat housing to make sure the thermostat
will operate. Something like this...

[Image: AEU86 AE86 - Hi from South Afrika]

Cheers... jondee86

The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.
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08-06-2018, 08:31 AM
Post: #4
Hi from South Afrika
Hi
Thanks for the reply.
And yes I do have some Dutch ancestry higher up in the family tree.

My engine is the some set-up as in the picture above, except for the water outlet at the back of the head. That is blanked off completely. My problem is that I keep blowing head gaskets, the last one lasted only a week, and the no. 4 cylinder is full of water. This after I had the head completely reworked new gasket and new head bolds and washers. This was my 3 head gasket with the same result.
I had the head pressure checked for cracks, and barely skimmed. I'm running out of ideas of what the cause could be other than the block might be skew or that the outlet at the back has something to do with water hot spots around the no. 4 cylinder.
I'm still running the standard supercharger, with a bigger pulley on the crank and a smaller one on the supercharger. I'm not even boosting a bar, so doubt that its over-boosting. I know these engines can handle a lot more than that.
the only other thing could be timing, I did not notice any detonation or 'Pinging' sounds. Just a sudden rise in temp and then I knew the gasket has gone...
Please if anyone can assist and give my some more feedback and ideas, I would appreciate it a lot.
Thanks.
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08-07-2018, 12:35 AM (This post was last modified: 08-07-2018 12:37 AM by jondee86.)
Post: #5
Hi from South Afrika
Oh well... another perfectly good theory shot down by reality Sad

Only kidding... I still think the theory holds good, and it looks as if these
guys think along the same lines....

[Image: AEU86 AE86 - Hi from South Afrika]

Where have you located the ECU and gauge water temperature sensors ?

Have you checked by feeling the hoses to make sure the thermostat is
actually opening at around 80degC and water circulates thru the radiator ?

If you warm the engine up with the radiator cap off, can you see the
water start to circulate when the thermostat opens ? If the thermostat
is installed back to front or if there is no bypass flow while the thermostat
is closed, it won't open until the engine has overheated !!!

Do you still have the possibility of fitting an outlet to the back of the
head ? If I was in your shoes and everything else checks out, I would say
fcuk the theory... I'm gonna fit an outlet to the back of the head and see
if that helps Smile

[Image: AEU86 AE86 - Hi from South Afrika]

You should be able to grab one of an AE82 and run a hose to somewhere
on the suction side of the water pump. Maybe the heater return line to
the thermostat housing is still there ?

Cheers... jondee86

The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.
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