Assist P38 to stop overheating ?

**p38arover** · 27th April 2009, 08:59 AM

Originally Posted by Remy

Hey Ron,

Is there any information about faulty water pumps that you know about. i replaced the radiator and thermostat and the car still got hot on those nasty days before the weather started to cool down but i didn't get enough time to test this a little more and since then it has been perfect. Talking to my mechanic he said that it could be that the impellers which are plastic in the water pump and if worn wouldn't pump enough water around? Just wondering if anyone has heard anything like this before.
Cheers,
Remy

The impellers are definitely pressed steel. I've replaced three of them! When you buy, ensure you don't get an AllMakes one - they won't last, the bearings collapse and, as the shaft tilts, it takes out the fan on the radiator. Go genuine or a well known brand, e.g., Quinton Hazell.

**p38arover** · 27th April 2009, 09:06 AM

Originally Posted by PhilipA

80c would almost certainly be too cold for the injection. Maybe 88C would be OK , but you would have to monitor it and maybe read up on the specs of the GEMS or Motronic. If it is a Bosch, call Bosch technical assistance. That will challenge them! If GEMS, email GEMS in UK.

Bruce Davis told me the thermostat in a P38A is an 88 deg C item. I know the general thoughts are that it a 96 deg C unit. I've not pulled a thermo housing apart to check. Has anyone got an old one they can open up?

My car runs with the needle just under the centre with an 88 deg C thermo.

Originally Posted by PhilipA

It is possible to machine a hole and fittings for a thermostat housing on the front of a Thor manifold as I have done it, but mine is on a V belt engine so I do not know if there is enough room on a 38A. if GEMS it should also be possible .
Regards Philip A

No need. The GEMS manifold is already machined to take the thermostat. Thanks for the info about the Thor manifold, Philip.

**tasi devil** · 27th April 2009, 12:58 PM

Ron thanks for info. ordered the aluminium 'tree' and thermostat from Davis Performance Landys [good blokes btw], as mine is a 1/98 P38 they didn't have the inline thermostat fitting for the top hose, so i'll probably get one manufactured locally, or look into what PhilipA has suggested.

.........tasi

**p38arover** · 27th April 2009, 03:03 PM

Is yours GEMS or Thor?

**tasi devil** · 27th April 2009, 03:15 PM

how do i tell ? i thought it was a GEMS but when i gave Dean the dates on the rego he reckoned it was a Thor. can you tell from a pic ?

..........tasi

**81stubee** · 27th April 2009, 04:00 PM

GEMS - Has engine capacity on the large rectangular Plenum Chamber, 4.0 or 4.6

THOR - Looks like a bunch of bananas for the manifold.

I brought an allmakes thermostat off evilbay for mine. It had imprinted inside 82 C as you looked down the large hole.

My temp gauge sits midway, which I found strange because before the motor swap it sat on about 1/3.

Stu

**p38arover** · 27th April 2009, 04:31 PM

Originally Posted by tasi devil

as mine is a 1/98 P38 they didn't have the inline thermostat fitting for the top hose,

Hmm, I'm not sure what that means. This is the hose fitting/thermostat housing on my GEMS engine. Is yours like this:

**tasi devil** · 27th April 2009, 05:34 PM

just went and checked, it's a GEMS...4.6 on top of plenum & flat belts. and yes it looks similar to the pic Ron except mine has got a sensor ? on top of the fitting.
so therefore if i've understood the discussion correctly the thermostat should fit in that housing ?.
Ron what the bloke at DPL was talking about as i understood it, they manufacture [have no stock at present] in aluminium a fitting of two halves which screws together holding the thermostat inside and appropriate sized tubes each side to connect in the line of the radiator hose. this was for a Thor motor.........which i will not be needing as mine is conclusively a GEMS

**p38arover** · 27th April 2009, 05:48 PM

Ahh, yours is like this (I wonder what the sensor is?):

If you remove that housing, you should find the inlet manifold has a recess around the hole and into which the thermostat sits.

Re thermostat temp, the workshop manual says:

The thermostat is closed at temperatures below approximately 80 °C (176 °F). When the coolant temperature reaches between 80 to 84 °C (176 to 183 °F) the thermostat starts to open and is fully open at approximately 96 °C (204 °F). In this condition the full flow of coolant is directed through the radiator.

So is this an 82 °C or a 96 °C thermostat (or something else)? Experts, please?

**p38arover** · 27th April 2009, 06:05 PM

Ahh, A little research shows the inlet manifold changed for GEMS engines from 1998. That sensor appears to be the coolant temp sensor. If you look at the pic of mine, you'll see mine almost hidden behind the otehr sensor. Can you read the part no. cast into the manifold on yours?

I wonder if that manifold has the recess for the thermostat?

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