Who knows and that is the problem. If you buy an aftermarket part you have no way of knowing whether it is made to the original spec or not. Due to the multiple pipes and the fact that the location of them is important, it isn't easy to bypass it. You could drill a few holes in the plate if you really must, or just pour boiling water out of a kettle into it and confirm it opens. If it does, then that isn't the problem.

 

Confirmed, the thermostat does not open.

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Just so a post does not go dead and provide useful information to others.

My odessy continues.

New fan clutch, new thermostat and new water pump. However, the radiator is not hot as it should be, it gets only warm and not burning to the hand.

Although the radiator was removed and flushed, it is very well possible that the coolant is not getting through the passenges.

Ordered a new one and will be installed next week.

Otherwise it's a case of a failed new water pump. I bought a branded one.

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Always test new thermostats before fitting. I always use my vacuum pump connected to the bleed hose when filling the system. (similar to this one on Amazon) That tends to suck all the air out as you add coolant. Then burp as usual by squeezing the rad hoses.

 

Thanks. Yes, thermostat tested and it opens.

Radiator is cold, so definitely something not working right. Pump, air or radiator.

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Do all the hoses get hot ? The flows on GEMS & Thor are like this:

 

I've also had an issue in the past with a seemingly good-flowing radiator, but in reality, not flowing correctly.

Hope the replacement of the radiator resolves your issue.

 

Thank you to all for your suggestions. New radiator going in on Friday.

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Radiator has been replaced, and is still overheating.

When touching the (also replaced last week) thermostat, one side is cold and the other hot, there is no flow.

This means I have another faulty thermostat or the new pump has failed?

I think that even with a failed pump the thermostat should open and the entire housing should get hot.

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Have you got the pipes to the thermostat connected correctly? See the picture posted by pwood a couple of days ago.

 

Have you got the pipes to the thermostat connected correctly? See the picture posted by pwood a couple of days ago.

Yes, you can't really connect them wrong, the size of the hoses and thermostat force you to connect them one way.

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I would like rule out any other issues and want to by-pass the thermostat - should I join #3 and #2 and #4 and #12?

 

Test the thermostat in boiling water. Much easier than trying to bypass it, and either way it needs to be removed.

 

This is the 3rd thermostat that has failed, the previous one being only 1 year old.



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You're buying crap then. I replaced the original stat on mine when the engine was rebuilt about 5 years or 200,000 miles ago. I ended up fitting that original one on another car and it is still working fine after a total of 25 years as is the replacement I fitted to mine. Buy cheap, buy twice.

 

Seems there are many of them.

It's only a thermostat, not rocket science.

The inline seems like a good way to rid myself if this problem entirely

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Or buy a decent one, it isn't that much for a genuine LR one Thermostat - Complete - V8 | Range Rover P38 considering the damage an overheat can do. Not sure how you can bypass it reliably as it is the heat from hose 4 that causes it to open. When closed coolant from hoses 4 and 12 are passed through to hose 3 and returned to the water pump. Once it opens, coolant from the bottom of the radiator joins in the flow with the other to the water pump.

You say you've tested the thermostat with hot water and it opens, so what makes you think it isn't? If you don't mind destroying your cheapo Chinese thermostat, take it off and drill a few holes through the valve plate. If that cures the overheating, then you have (had) a duff thermostat. If it doesn't, the problem is elsewhere.

 

Or buy a decent one, it isn't that much for a genuine LR one Thermostat - Complete - V8 | Range Rover P38 considering the damage an overheat can do. Not sure how you can bypass it reliably as it is the heat from hose 4 that causes it to open. When closed coolant from hoses 4 and 12 are passed through to hose 3 and returned to the water pump. Once it opens, coolant from the bottom of the radiator joins in the flow with the other to the water pump.

You say you've tested the thermostat with hot water and it opens, so what makes you think it isn't? If you don't mind destroying your cheapo Chinese thermostat, take it off and drill a few holes through the valve plate. If that cures the overheating, then you have (had) a duff thermostat. If it doesn't, the problem is elsewhere.

An "inline kit" has been done many times for the Thor model.

 

The part you linked is a Britpart, probably another cheapo as well.

I put back the old thermostat and now it isn't overheating. Seems it is getting stuck at times.

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The page I linked to gives the options of Britpart, Allmakes, Bearmach and Land Rover (although if you are looking at it on a phone, I've no idea what it will show you). If putting the old one back seems to prove you had a duff one, get a decent one and fit that.

 

I just put this on last week while changing to a new lower thermostat to water pump hose and it has been running great. Also make sure to only USE distilled water or the minerals will attack the thermostat/waterpump.

Pardon Our Interruption...

 

Yes, this looks like one of the many generic thermostats - I have ordered another one. The ultimate solution is to replace it with in inline kit.

 

It seems #4 on the GEMS is the equivalent to the hose that is eliminated on the Thor model. This acts only as bypass when the thermostat is closed.

 

Seems this has been done many times before.

 

Other solutions, evidently this is a recurring issue.

 

Land Rover Range Rover P38 THOR Inline Kit

inlinethermostats.com

and here

EKM | Account Cancelled | Account Closed

The online shop you were looking for has been closed. Please contact customer support on 0333 004 0333.

shop.v8engines.com

 

That kit is from RPi, a company I have had dealings with just once and would never, ever use them again or recommend anyone else to use them. They are the same company that will tell you that every single LR V8 will slip a liner so they can sell you a custom made engine block for £8k.

What that conversion does is back engineer the P38 cooling system to the same as the Classic. Fair enough, it probably works (ish) but obviously Land Rover didn't think it would or they wouldn't have changed it.

 

One should not immediately assume that just "because they (engineers) didn't think of it" it must be impossible or the best solution.

Many engineering and production decisions are based on completely different considerations that have little to do with reliability; the single most important objective for any automotive company is to be profitable.

I can say without a doubt that Land Rover did not foresee or even desire to see P38 driving around after nearly 30 years and with 400,000KM on the odometer - this was never a "design consideration".

I am currently in touch with these people:

 

You've missed the point. Whether it is plastic or not is irrelevant, it is an additional component that the Classic didn't use so there must be a reason why the cooling system design was changed from that used on the Classic. Many modern components on cars of every make are now plastic and I suspect you will have great difficulty finding a car built since the mid 2010;s that doesn't have plastic cooling system components but it isn't that fact the housing is made from plastic that has caused you problems. The actual thermostat inside the housing is just the same as any other thermostat irrespective of where it is located. If it doesn't work then you have the same problem.