How hot does it get to on the gauge? Do the fans actually work? they should start to kick in at just over 90 degrees.

 

They kick in about 95ish but the gauge goes up a lot higher. its been up about 110.
I am unsure if the fans are sufficient enough and have no idea what the resistor blocks are for.

It cools down if I put the interior fans on full hot.

 

Does it over heat during normal driving, or only once you stop/get stuck in traffic?

 

Normal driving it still creeps up. once you stop if the fans are not on full it rockets up.

 

Change the thermostat whilst you have the system apart would be good idea and to be super sure check the water pump. Reverse flow the block whilst you are on too.

 

the thermostat is out just the housing is left on. decided to remove it to rule it out.
how do I reverse flow the block? and how do I check the water pump? is there a check I can do that wont involve taking it out?

 

The water pumps can fail, the impeller can come lose on the shaft so its no longer turning, you could also have a blockage somewhere. Flushing it out backwards and then forwards (can use a hose pipe if the engine is cold and not running). With the rad hoses off while flushing through you will soon see if there is any kind of blockage in the engine or the rad itself (make sure your heater is set to full hot while doing this). To check the pump, you can normally see a good flow going back to the header tank through the small bypass pipe while it's still warming up. You can also very briefly fire it up with the top left rad hose off to check the flow, it should come out at a good rate.

 

Should not run an engine without a stat long term as it can cause overfuelling due longer warm up times.

 

Perfect i will try flushing it this week. The thermostat was only removed as a tempoary test to see if it was the cause i will fit one once i have the overheating issue sorted.

Thanks for the help.

 

So today I removed the radiator and attempted to.flush the engine. Water in the driver side coolant hose and it's flows pretty good out the other side. water in the passenger side and not much flow. I couldn't get the heaters set to hot as it has digital ones and the battery was dead so it is on charge now.

Does that sound right?

 

It should flow better right to left as you look at the engine really, that's the way it was designed to flow. You should really check the pump as well though, but with the rad heating up and the fans cutting in it must be pumping at least something round.

 

Hi Bob , I'm familiar with your z20leh transplant,

Question please, did you leave the auxiliary pump in place?

This would have had to be a retrofit, as you will know, the layout of comparison water pipes slightly differ, ,

I will recognise your pipe layout from pictures.

I wish to help and advise if I can

B

 

Hi,

I will get some pictures tomorrow.

I dont think I have an auxiliary pump. Does it come on the LET or the LEH?

Also what does the aux pump do? Is it required?

Bob

 

Hi,

I will get some pictures tomorrow.

I dont think I have an auxiliary pump. Does it come on the LET or the LEH?

Also what does the aux pump do? Is it required?

Bob​

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​

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Hi Bob , The Z20let engine has an auxiliary water pump fitted to her F23 gearbox, the water cooling flow re- routes itself ,

Note;; without the engine ON

On ignition the aux water pump sends coolant around ,

On start up , there is the obvious timing /belt /water pump.

So in effect the z20let engine did have a n extra coolant facility,

Note;; Vx deleted this pump , with their newer engine The Z20leh,

This engine , differs in coolant direction.


The pump apparently according to VX experts isn't required, I THINK IT IS, Ie cost effective

After all I fitted It and it works.

This might be wrong but if it flows in the "normal" direction OK and not in the reverse position I would have thought that this indicates probable pump impeller problem. It should flow equally well in both directions so pump or blockage is my guess.

You IMO , are right,

The Impellor on the water pump doesn't work,

There is a very easy test LOL

Simply make sure you have flow of coolant !!!!

You can see it visually with the engine running,


Please look at your header tank, to see if there is any visible flow of coolant, if there isn't then you have water pump failure IMO,





B

 

This might be wrong but if it flows in the "normal" direction OK and not in the reverse position I would have thought that this indicates probable pump impeller problem. It should flow equally well in both directions so pump or blockage is my guess.

 

By the way what size engine and description is the LEH engine?

 

Bob, It isn't that easy,

Pics soon of how it should be

B

 

The resistors in the wiring for the rad fans is to simply alter the supplied voltage thus changing speed of fan. (Variable speed fan ya can use opcom to test)
Not sure if it impacts the functionality of slim line fans (suppose it depends if motors can operate correctly at different voltages)

 

I was at my garage yesterday fixing another car.
But when I was there my mate noticed that the coolant hoses going to the Heater Matrix were pressurised.

How can this be when I have no radiator fitted?
I think it is from when I was putting water in the coolant hoses. but I didn't think it would have held any pressure with the radiator not fitted.

 

Coolant has to flow to the heater matrix efficiently . You could possibly have a blockage there,

The hoses expansion says it all, even though you say there is no rad fitted , the hoses are expanded,

That is your clue to your progress.


B

 

Are all the hoses routed correctly? You say the hose is expanded. Is there water in it or has the hose just collapsed structurally and expanded?

 

There is no water in the header tank. I have removed the radiator and put a hose onto the coolant hoses.

All hoses were new when i changed the engine. i have Roose motorsport hoses fitted.

Does anyone have a diagram of the hose routing for a Z20LeH in a MK4? I am also using the VXR radiator pack,

 

YUP If I can find them lol.

B

 

Come across these for now.





















Aux pump in the last 3 photos



B

 

So what you are saying is you have put a hose on one of the heater pipes with the other end open and the first hose is in fact full of water with no flow through the heater matrix?

 

Sorry for the late reply.

The Astra has been put on hold for just now, I have recently found out my girlfriend is pregnant so been busy moving into a bigger house etc.

I will get back to the Astra once we are moved in a settled. Thanks for all your help guys I may need some more once I get back to it.

Thanks again.

Bob

 

Best of luck with junior!