P38 underheating!

I posted a while ago about my vehicle not getting warm enough. Anyway I carried on with a new allmakes thermostat(petrol v8) it was not reaching much more than 75degrees c obviously in summer/ autumn it wasn't really a problem. Went for a 100 mile drive and it was 15-20 miles before the heater really worked and tbh the cab only heated up properly on the journey back. Managed 20 mpg though! I definitely think it 10-15 degrees short. At 50 (due to roadworks on the m6) the engine was definitely not up to temperature due to the wind chill. Anyway the point is don't buy a cheap and nasty stat buy a gates. I've just ordered one for £60 delivered of the bay. Hopefully I'll squeeze a couple more mpg out of the old sow when it's up to proper temperature.
Engine temperature is completely vital in an efi engine to low to high both are equally devastating. The temp gauge was at the bottom of the blue at 50. I don't think it was warm enough to allow the heater fans to work hence the sub zero heaters!
Jb

Like my 'Non LR thread, I bought a stat (FirstLine) and had intended to change it if needs be.
Even though the car got to temp quickly (for a Diesel) I pulled old stat and compared like with like.......no comparison really, the original was a 'Thompsons' (never heard of them) but it was way better built than the poxy FirstLine.

Thompson original duly popped back in.

Are you completly sure you have bleed the coolant system properly? If the heater matrix is air locked you wont get any or hardly any heat.
You can back flush it by removing the heater hose, one at the back not front and just use a hose gently to flush it. Block off the metal pipe it attached to remove the header cap and let all the air and water overflow from there.

It's not just the heater it's the gauge and the ecu showing low temps. As I say it's not really a problem when it a bit warmer but obviously minus temps and the wind chill on the rad. Also on the way back ( 2nd 50 miles) it had warmed up enough that the cab was warm. Im certain the stat is either open all the time or opening very early. Keeping hot coolant in the engine(and matrix) not cooling through the rad when it gets really cold. The gates stat opens at 82 which suggests the engine runs in the late 80s.

Take the thermostat out, and test in a kettle, measuring water temp with something like this on fleabay.

Then if it opens at correct temp, re-install thermostat and bleed properly.

Trust me the allmakes is going in the bin. The gates will be reinstalled. And if it doesn't cure my problem I promise I'll come on here and say so. Then you can call me a pillock!
Jb

johnnyb70 said:

Trust me the allmakes is going in the bin. The gates will be reinstalled. And if it doesn't cure my problem I promise I'll come on here and say so. Then you can call me a pillock!
Jb

Click to expand...

Allmakes about the same quality as Britpart. In fact, I wonder if it is Britpart rebranding itself.

I replaced the thermostat on my jag as it wasn't getting up to temp. I brought one from euro car parts. Putting the two side by side was hilarious. The original jag stat was huge built like a tank. The ecp one was ridicously undermade the spring was half the gauge no jiggle pin etc etc. But it did open at the correct temperature...... For now!
Jb

I've today replaced my p38 thermostat with a new gates one. Not to bad a job if you can use the rad drain. Anyway to cut a long story short I'm back to running at the middle of the gauge. Also 2 mpg better economy and the heater works. What's not to love. The old one wasn't really busted justed opening way to soon. At the weekend I also replaced my mgb stat( Vauxhall 20seh engine) that one was not closing properly as it was canted over(both valves) for some reason. What a pig of a job all three housing bolts snapped had to be drilled and tapped. That also quickly reaches temperature now but the plugs were sooty from running cold and had to be cleaned off. Such a simple device is beyond vital in an efi engine.
Jb