Hi All,

I have read a little around the subject and understand that you should top up the car to the Cold Level line and then turn the engine on without the filler cap on.

All the other cars I have had, had a min/max line and a semi opaque coolant tank...the p38 on the other hand doesn't seem to have either. This makes it more difficult to fill to the correct level.

I presume when filling up the coolant its just to c. 1cm below the seam that can we seen by looking inside the tank. Does the filling need to be that accurate or is filling to the seam sufficient? Ie. Is there a room for error when filling?

Thanks,

Tom

The tank was originally see through, they go opaque with age so you can no longer see the coolant level through them.

I changed mine for that very reason, I got tired of having to shine a torch through it to be able to see the coolant.

A cm below the seam is about right. The trouble with filling too high is that as the coolant expands with heat, the excess will blow out the overflow. If you continue to top to a level that is too high you will think you have a leak when you don't. The seam might be okay, but may be marginally too high.

Another useful way is to check the bottom end of the overflow brass pickup little pipe - the one you see when you open the cap - it should be "wet" drowned in at least 1cm of coolant, not "dry".
Better to have a lil less coolant than too much, for the reasons illustrated above ...

They all seem to have a very slightly different 'comfortable level' - try as I might, I have never got mine to sit at the top-up level and stay there. There's a fair amount of expansion and contraction going on.

What I have done on mine after the first drain and refresh (not a full drain-down, that's slightly involved) and making pretty sure it's bled right, heater's coming on hot etc, is to mark the level on the tank in pencil (even if it's gone opaque it might give an idea, could always use a strip of card to dip-check it and compare).

There's now a pencil mark for cold and sitting still and a pencil mark for warmed up a bit, switched off. Both are below the 'fill to' mark on each car. The two engines have slightly different happy levels to them, but they are (and also all other P38s I've seen/driven/worked on) both in the same rough area.

I have to agree that trying to keep it at the seam is hopeless......At least for Bolt.
If I fill to seam with it cold, within a few driving cycles, it is back down to 25mm below the seam.
It then stays there. So, if it was indeed a leak, it should continue to leak out, but this does not happen.
The Borrego likes to sit at 15mm below the seam, and is also stable there.
They must just be blowing the "excess" coolant out when they get nice and hot.
I recently bought a nice new tank for Bolt so I can see the coolant very well. Borrego is not too bad with the stock tank.
Just wish these things had a coolant level switch! (I know, other threads cover this)

Bolt wrote:

They must just be blowing the "excess" coolant out when they get nice and hot.

The Thor does - if I fill it a bit more than I meant to it soaks the wing. The Gems must do, but I've not seen/noticed it happen. On my -sample size of two- comparison, the Gems seems to run at a lower overall pressure - although it's improved since the thermostat finally gave up, reckon it'd been dying for a while. Gets warm now. *

-*The Bosch car is also dosed with radweld frequently, which I hate tbh, and isn't mine - I just have a good look over it from time to time when I use it. The Gems is my main car and is not allowed radweld/k-seal or similar the only car I've got that I'd consider using them in is a Citroën flat twin, and for obvious reasons that isn't going to happen.

I am thinking of getting a new coolant tank so it is easier to check my coolant level. Should I go for a Britpart version or OEM? The price difference is nearly double but I hear the OEM is better quality?

OEM stands for Original Equipment Manufacturer so will, or at least should, have been made by the same company as made the original one. Britpart may be from the same supplier but sold to Britpart in bulk and sold through them or may be a cheap Chinese made copy, you never know.

Sam, Your asking for trouble putting any rad products in a p38, I’ve taken rads out that we’re totally blocked, they don’t have the biggest of water ways,

I was talking to a friend about this topic and he mentioned asking whether the disappearing coolant some of you are experiencing could be down to airlocks in the system dissipating?

Any airlocks will have disappeared and made their way to the header tank after 2 or 3 starts and a bit of a run, so if it always does it, it's either blowing excess out the overflow or you've got a leak.

Thanks again Richard.

Is the V8 expansion tank or Disco 2 TDI a replacement for the 2.5 diesel?

No, the V8 P38 and TD5 Disco use ESR2935 (supersedes to PCF101410) and has an extra spigot at the front used for the throttle body heater on the V8 (no idea what the TD5 uses it for). Correct one for the P38 diesel is ESR2936 which supersedes to PCF101420. See https://www.island-4x4.co.uk/expansion-tank-25td-britpart-esr2936-pcf101420-p-2741.html (yes I know it's Britpart but it's the first listing I came to with a proper description).

The one used for the throttle body heater on the V8 is used for the return from the EGR cooler where its fitted to the TD5.

no10chris wrote:

rad products in a p38, I’ve taken rads out that we’re totally blocked, they don’t have the biggest of water ways

Cheers, totally agree. I can't count the number of times I've heard 'it had a leak' followed by 'so I put radweld into it' followed by 'it blew all its coolant out and overheated again' - If that car doesn't have half its liners dragged into strange positions it's a lucky one. Something I'm mildly paranoid about on the HSE tbh. I use it from time to time for work, my daily car is my GEMS and also my to-and-from site vehicle most of the time. One of these days I'll take the Thor to bits (if there's anything left of it) and have a good look at it. Even worse, last time I checked it the Bosch had water not coolant, and as a lazy sniff test all I got was a nose full of hot radweld vapour. Great. It's also impossible to stop other people mixing coolants if they do use it. Pink plus Blue seems to make a nice sludge. Flushed the GEMS out as best as I could when I first got it (it had meths-purple coolant and the people indicated as having serviced it - I rang and asked - said it was likely screenwash, probably right actually). Runs on 50/50 blue now.

I used radweld once in a Renault 5 I had back in the 90's. Didn't help at best. Decided it's counterproductive in the main. I can't imagine what it does to the convoluted paths coolant has to take in the Rover engine.

You can pop the top and bottom off the rads, although a PIA bending all the stainless steel tabs up, I couldn’t find anything to hand at the time that would of gone through the fins, but to be honest I don’t think I would of got through any of them, I had fixed a hose to the bottom pipe , turned on and nothing came out the top, lol

Interesting.

When I got mine, it had an original alloy/plastic radiator. Whilst the coolant level never moved, the temperature would creep up in our wonderful traffic jams.

On the advice of a local '38 owner, I had a "traditional" radiator made. This was a lovely job, fitted perfectly and, more to the point, I can get it repaired in any radiator shop.

However, topping up to the "Cold" level, it will drop to about 5mm below, then never move. Of course, when I first fitted the rad, and replaced all the hoses, I was paranoid. Now, I'm used to it and don't top it up any more. Temp stays bang in the middle, no matter how slow the traffic.