Hole in thermostat

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
THE BUDDAH

THE BUDDAH

New Member
Posts
686
Location
Romford essex
Hello,

Has anybody come across this solution.
My range rover p38 overheats sometimes and there is no patern to when it happens except that it usualy plays up when im dress up smart and going out and don't want to get dirty.

I'll stop the car take off the resevouir cap. when the car is still quite hot keeping the car running and top up the lost water with fresh....result...the car runs fine for about a couple of months then then overheats once again.

Iv'e been told to drill a 8mm hole in the caseing of the therostat and that will do the job. The thermostat is new and has been in the car four six months. I've just received a new thermostat in the post and after putting it in boiling water it failed to open, i tried this three times.same result.

How do i stop my car from overheating.
Im off to devon soon 300mile trip.....a bit worrying

Any good advice.

Mike.
 
You're not alone, I worry about driving into Devon as well, there's some right weird folk living down there.

The old trick of a hole in the thermostat was to help when you're topping up the system. It made sure that you didn't have air below the stat. A small hole won't do any harm but I'd be more interested in where the coolant has gone that you're replacing when you top up.
 
THE BUDDAH said:
Hello,

Has anybody come across this solution.
My range rover p38 overheats sometimes and there is no patern to when it happens except that it usualy plays up when im dress up smart and going out and don't want to get dirty.

I'll stop the car take off the resevouir cap. when the car is still quite hot keeping the car running and top up the lost water with fresh....result...the car runs fine for about a couple of months then then overheats once again.

Iv'e been told to drill a 8mm hole in the caseing of the therostat and that will do the job. The thermostat is new and has been in the car four six months. I've just received a new thermostat in the post and after putting it in boiling water it failed to open, i tried this three times.same result.

How do i stop my car from overheating.
Im off to devon soon 300mile trip.....a bit worrying

Any good advice.

Mike.
Click to expand...


buy a thermostat that works firstly. some thermostats had those lil holes in them already, so wouldnt worry about drilling one in if necessary.
...r u saying you top up every few months only? that isnt so bad
 
THE BUDDAH said:
Hello,

Has anybody come across this solution.
My range rover p38 overheats sometimes and there is no patern to when it happens except that it usualy plays up when im dress up smart and going out and don't want to get dirty.

I'll stop the car take off the resevouir cap. when the car is still quite hot keeping the car running and top up the lost water with fresh....result...the car runs fine for about a couple of months then then overheats once again.

Iv'e been told to drill a 8mm hole in the caseing of the therostat and that will do the job. The thermostat is new and has been in the car four six months. I've just received a new thermostat in the post and after putting it in boiling water it failed to open, i tried this three times.same result.

How do i stop my car from overheating.
Im off to devon soon 300mile trip.....a bit worrying

Any good advice.

Mike.
Click to expand...

You only need a small hole (3mm) to let the air through but make sure its drilled close to the edge of the thermostat flange, when fitting the hole must be placed at the top. Those old enough will remember the "Jiggle Pin" a standard part of an old style thermostat.
 
This how it starts I'm afraid. Using my last experience you've probably got another 3 or 4 months of the occasional boil up and then the 'slipped liner' problem will become fully apparent and you'll be looking for another engine. You'll probably change or chemically clean the radiator, change the water pump and the header tank cap. But just save time and money and start thinking about that top hat liner repair or a low mileage engine of ebay! happy days eh?
 
Here goes,

First of all thanks for your replies. :)

The thermastat thats in the car worked six months ago when i bought it, i tested it the same way as the new one i just bought that does not work.

The loss of water/coolant fluid is caused by me when i loosen the cap on overheating to aid the cooling process. Once cool enough i then take the cap off completely and refill with fresh water (compliments of whoever answers their front door...lol).

It makes sense putting the hole at the top.

Liners..........Have i been misinformed? i thought that the bmw engine did not have liners.

Mike.
 
Last edited:
THE BUDDAH said:
Here goes,

First of all thanks for your replies. :)

The thermastat thats in the car worked six months ago when i bought it, i tested it the same way as the new one i just bought that does not work.

The loss of water/coolant fluid is caused by me when i loosen the cap on overheating to aid the cooling process. Once cool enough i then take the cap off completely and refill with fresh water (compliments of whoever answers their front door...lol).

It makes sense putting the hole at the top.

Liners..........Have i been misinformed? i thought that the bmw engine did not have liners.

Mike.
Click to expand...
It's a diesel? BMW M51 lump?? No liners. Overheating on that engine is likely to be RAD, viscous fan, or water pump if it's not the stat. Check that the viscous fan is running properly when the motor is hot and that the RAD gets hot all over particularly at the bottom.
 
Hi Datatek,

Thanks for that, i will remove thermostate again, test it and flush the whole system once again, but this time i'll drill that hole as well before replacing (so long as it works). Then i'll look out for the bits you mentioned.

Its a strange one as the car only overheats sometimes as i said before.
After the last episode the car has been fine, it just seems to warm up quicker. Im told thats due to the psi box i just fitted.

And yes....(just incase you was going to ask..lol) the car did overheat before the psi box was fitted unfortunatly over 100 miles away from home in the raodworks section single file of the m6 and of course during a so called nice weekend trip.....not so funny.

On that occassion i flushed the system through and the car was fine for about a ten months then wallop all started again.

Since that time i have driven the car to devon AND BACK ...lol with no problems, but then its come back to haunt me again on this occassion

Mike.
 
Last edited:
THE BUDDAH said:
Hi Datatek,

Thanks for that, i will remove thermostate again, test it and flush the whole system once again, but this time i'll drill that hole as well before replacing (so long as it works). Then i'll look out for the bits you mentioned.

Its a strange one as the car only overheats sometimes as i said before.
After the last episode the car has been fine, it just seems to warm up quicker. Im told thats due to the psi box i just fitted.

And yes....(just incase you was going to ask..lol) the car did overheat before the psi box was fitted unfortunatly over 100 miles away from home in the raodworks section single file of the m6 and of course during a so called nice weekend trip.....not so funny.

On that occassion i flushed the system through and the car was fine for about a ten months then wallop all started again.

Since that time i have driven the car to devon AND BACK ...lol with no problems, but then its come back to haunt me again on this occassion

Mike.
Click to expand...

My first thought going on that would be the viscous fan. Try shoving a rolled up newspaper into the blades with the engine hot (mind your hands though), if it stops it's shot. I can give you a mod to bring the aircon fans on either as a back up or to replace the viscous:) Not a good idea to use a PSI box until you sort out the over heating, if it keeps happening you will end up with a cracked cylinder head:eek:
 
THE BUDDAH said:
mod?
Click to expand...
A simple wiring mod that will allow the aircon fans to be operated either manually with a switch or with a thermostat. PM me if you want a drawing:) Always assuming your car has aircon of course.
One more thing, check that the expansion cap screws down fully, mine goes very tight about 2 turns before it is fully down.
 
Hi datatek,

I took the car for drive about 12 miles this morning.
No overheating. I checked the fan, the one in front of the rad. It stopped when I put a soft pipe up against it while the car was still running.
If fact I could stop it with my hand on second attempt.
So does this mean I need a new fan?
Should there have been resistance to stopping the fan?

Mike.
 
THE BUDDAH said:
Hi datatek,

I took the car for drive about 12 miles this morning.
No overheating. I checked the fan, the one in front of the rad. It stopped when I put a soft pipe up against it while the car was still running.
If fact I could stop it with my hand on second attempt.
So does this mean I need a new fan?
Should there have been resistance to stopping the fan?

Mike.
Click to expand...

With the engine hot it should have chopped your arm off:eek: Viscous fan is shot.
 
Hi Datatek,

I just tried the fan: the temperature gauge was around the quarter mark or just before half way after driving 3 miles.
I got my son to rev the car while i put a flexible rubber tube between fan blades and there was no response from the fan.
The fan was free wheeling.
Im going to go for a drive in a moment to get the car warmer for one last try.
Whats the difference between a viscouse fan and any other that might fit on the p38 2.5tdi?

I'll tell you how i get on.

Mike.
 
THE BUDDAH said:
Hi Datatek,

I just tried the fan: the temperature gauge was around the quarter mark or just before half way after driving 3 miles.
I got my son to rev the car while i put a flexible rubber tube between fan blades and there was no response from the fan.
The fan was free wheeling.
Im going to go for a drive in a moment to get the car warmer for one last try.
Whats the difference between a viscouse fan and any other that might fit on the p38 2.5tdi?

I'll tell you how i get on.

Mike.
Click to expand...

The viscous is the only fan unless you remove it and go electric. Electric will improve warm up in winter and makes a small but noticable improvement in fuel consumption.
Your viscous fan if fecked:eek:
 
Hello again,
I just took the car out drove in traffic for ten mins let the car idle for ten mins, drove in traffic ten mins then onto a motorway road drove with revs higher than usual. excellereated to 70 for a couple of miles. The car temperature was bang in the middle of the gauge. back onto a A road pulled over got my son to rev the car and i checked the fan, it was harder to stop the fan than before but i could stop it. Drove home 10 mins drive.
RESULT...THE CAR DID NOT OVERHEAT.

I don't understand it.

Mike.
 
You must log in or register to reply here.

Similar threads

feyniriel
P38 2.5 diesel engine overheating
Replies
5
Views
324
Grrrrrr
Grrrrrr
A
Gearbox max 3rd in auto mode
Replies
1
Views
348
Bemble
B
DollyBird
P38A Searching for die hard P38 guru - EAS
Replies
9
Views
634
brianp38dse
brianp38dse
Stev
suspension in extended mode and Suspension failure
2 3 4
Replies
68
Views
3K
Stev
Stev
Lucknow Landy
Running hot after a new thermostat
2
Replies
24
Views
2K
Jack Handle
J
Back
Top