Assist P38 to stop overheating ?

[tasi devil]

it has been mentioned many times here that P38's have a proclivity to overheat. as i understand it, due to the factory thermostat being set at 96'C., and blocked radiators. once overheated the engine is basically 'cactus' due to slipped liners etc. then big $$$$$'s to fix
so i had the radiator serviced and will keep it so.she's off the road [and has been for awhile] till we get the codes sorted for Faultmate diagnosis to reset the new Arnotts GenIII.,opening up exhaust, bigger injectors,new leads/plugs,service compressor/valves, dual battery system [Odyseysx2],new filters,low profile bars fr/rr,underbody protection.
in talking to my mate/mechanic about the thermostat, he suggested some options, drill some holes in rim of existing thermostat or put one in that opens at a lower setting. i should mention these blokes are very good knowledgeable mechanics and have/still do a lot of racing, circuit and speedway.
what are your thoughts re thermostat and keeping temps down ?

[81stubee]

Ron has put a 3.9 Thermostat in its original location in the manifold, and has purchased a alluminium junction piece to replace the current thermostat. I heard recently that the reason Landrover moved the thermostat was to reduce the risk of cold shock in extremely cold area's such as canada etc. I was thinking about doing the same, but for the moment will use the current setup.

Stu

[p38arover]

One can't remove the thermostat from the housing on a P38A so drilling holes in it or replacing it will be a tad difficult.

However, help is at hand. When Davis Performance Landys rebuilt my 4.6 thjey fitted an 88 deg C thermostat in the standard position for all previous Rover V8s and I fitted one of these straight-through sputniks in place of the thermostat housing. It was purchased from Davis.

https://www.aulro.com/afvb/images/imported/2012/02/1184.jpg

See also this thread: RangeRovers.net • View topic - Possible to Change Location of Thermostat? (http://www.rangerovers.net/forum/viewtopic.php?f=3&t=18448)

[tasi devil]

fantastic, geez you blokes are good, just read the link. thanks Ron will pass the info on and if you'd be good enough to post a phone number for Davis Performance Landy's i'll get one ordered and posted.it's gunna be a coupla weeks before she's on road, got a holiday coming up next week. holidays and owning maintaining a P38 :o
thanks again.

...............tasi

[p38arover]

Davis Performance Landys (http://maps.google.com.au/maps?hl=en&um=1&ie=UTF-8&q=davis+performance+landys&near=Sydney+NSW&fb=1&split=1&gl=au&view=text&latlng=15548516774020697282)


233 Annangrove Rd Annangrove, NSW 2156 - (02) 9679 1978

[johnlamont]

Cleanliness of the cooling system is vital to ensure that overheating does not take place irrespective of any other factor. If your vehicle is not subject to emissions testing I would opt for 80 degrees if that could be shown to increase reliability, otherwise just keep your radiator clean. Removal of the top and or bottom tanks and a professional clean followed by new coolant would be a must for any engine if the slightest doubt persists about the situation. John

[p38arover]

80 deg C might be too cool for the engine management system.

I tried getting a P38A radiator cleaned but the radiator shop said they couldn't get the crimping thing around the header tanks.

[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

[Grumbles]

For the potential damage which can occur and to avoid it I'd suggest looking at the water pump as a consumable/maintenance item.

[PhilipA]

I am not an expert on 38A cooling but I would like to make a couple of observations.
1 if you drill holes in a thermostat the car will never warm up on a cold day.
I once went to Katoomba in winter and the car went cold. Went home and pulled the thermostat and it was not fully closing, just by a tiny crack.

2 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.

3 the reason for the bypass thermostats is to reduce pollution to meet the later stringent regs, as most pollution from an engine is just after start up and warm up. The bypass thermo is also the reason for the Freelander 1 disasters.

BTW there were a lot of recalls on early 38A, because the top rad hose was above the rad and airlocks formed. LR tried 4 or 5 different designs.

Make sure you have one of the later top hoses. Also early cars used to blow heater hoses because of poor quality. Had one happen to a car in our club on an off road trip to Mt Airlie. AFAIK it was these issues that caused most grief to early 38As, as they would overheat and bye bye engine.

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

[p38arover]

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]

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.


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]

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]

Is yours GEMS or Thor?

[tasi devil]

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]

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]

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:

http://www.aulro.com/afvb/attachments/p38a-range-rover/15125d1240817484-assist-p38-stop-overheating-p38a_thermo_housingw.jpg

[tasi devil]

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]

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

http://jimsrover.afraid.org/rover/chrisall_stat1.jpg

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

http://jimsrover.afraid.org/rover/chrisall_stat2.jpg

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]

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?

[tasi devil]

yep that's it Ron, sensor is in the same place.
i've just been down to the workshop the boys were still there and the number is HRC2616.
when the bits arrive from DPL we'll pull the fitting off and have a looksee.

[p38arover]

Looks to be the same casting number as mine. Let's hope it has a machined recess.

[tasi devil]

will certainly let you know. could be end of next week before i get to it , going out to an island in Bass Strait with a coupla mates for a holiday.

........tasi

[p38arover]

Have some King Island Brie for me! Enjoy your few days away.

[tasi devil]

Have some King Island Brie for me! Enjoy your few days away.

is it ok if i have a fairly decent red to go with it ?

[p38arover]

is it ok if i have a fairly decent red to go with it ?

Absolutely! I'll be having a few soon.