Coolant disappearing, not overheating

[Mark-ixql7]

Hi all

I just picked up a chimp a couple of days ago. The previous owner had mentioned the coolant level always looks low in the expansion tank but it doesn't overheat. It was a 5 hour drive home, and he appears to be correct in that according to the temp gauge, it never went above 80c iirc.

I topped it up to half way yesterday and did about maybe 70 miles, and it was back to the bottom of the tank but again wasn't overheating. I checked the swirl pot and that's to the brim (and looking cruddy... First job!).

Seems a bit weird. I can't see any obvious leaks and once it's reached near the bottom it doesn't seem to budge from there. Normal, or any ideas what I should be checking here??

Cheers

[Wombat3]

Mark-ixql7 said:

Hi all

I just picked up a chimp a couple of days ago. The previous owner had mentioned the coolant level always looks low in the expansion tank but it doesn't overheat. It was a 5 hour drive home, and he appears to be correct in that according to the temp gauge, it never went above 80c iirc.

I topped it up to half way yesterday and did about maybe 70 miles, and it was back to the bottom of the tank but again wasn't overheating. I checked the swirl pot and that's to the brim (and looking cruddy... First job!).

Seems a bit weird. I can't see any obvious leaks and once it's reached near the bottom it doesn't seem to budge from there. Normal, or any ideas what I should be checking here??

Cheers

My guess would be that there's a leak somewhere that kicks in once the pressure gets above a certain level. When the tank is emptier then the pressure in the system will not get as high & therefore it stops leaking (or it doesn't leak as much or as fast)

Suggest get hold of a cooling system pressure test kit, pump it up to about 1 bar & leave it overnight & see what happens.

[glow worm]

Don't overfill the expansion tank , you only need 2 centimetres otherwise it will just come out through the pressure cap when its running. Dip the expansion tank and monitor the level, it will find its own level .. you don't need to keep topping it up ... If you do , then you have a problem. The level in swirl pot is most important. The clue with the expansion tank is , it's in it's name .... for expansion. I always top up through the swirl pot ...

[dudleybloke]

Could be a pinhole leak somewhere that is only a problem when at pressure,

[bobfather]

glow worm said:

Don't overfill the expansion tank , you only need 2 centimetres otherwise it will just come out through the pressure cap when its running. Dip the expansion tank and monitor the level, it will find its own level .. you don't need to keep topping it up ... If you do , then you have a problem. The level in swirl pot is most important. The clue with the expansion tank is , it's in it's name .... for expansion. I always top up through the swirl pot ...

^^this^^

The expansion tank is too small to accommodate the increased volume when hot. No more than 1/3 full when cold, any more and it'll eject water through the relief cap when hot

[Loubaruch]

+1

As Glowworm says do not keep filling the expansion tank!.

If you think about it most TVR Griffith or Chimeras will have had several replacement radiators by now and the chances of the capacities of these remaining the same is pretty slim. Some owners will have fitted completely different rads e.g. aluminium no doubt of a completely different capacity to original so its not surprising that expansion tank levels vary. The level in the expansion tank of my Griffith 500 always stabilises to just above the bottom outlet no more than 0.5 cm. If I try to even fill it a couple of centimeteres it will just eject it when up to temperature.

Never any overheating problems since the last radiator change about 10 years ago.

If you have a coolant leak it will most likely be evident when the car has been standing for a few days, generally around the bottom of the radiator.

[Classic Chim]

bobfather said:

glow worm said:

Don't overfill the expansion tank , you only need 2 centimetres otherwise it will just come out through the pressure cap when its running. Dip the expansion tank and monitor the level, it will find its own level .. you don't need to keep topping it up ... If you do , then you have a problem. The level in swirl pot is most important. The clue with the expansion tank is , it's in it's name .... for expansion. I always top up through the swirl pot ...

^^this^^

The expansion tank is too small to accommodate the increased volume when hot. No more than 1/3 full when cold, any more and it'll eject water through the relief cap when hot

Exactly this. 1/3 full expansion bottle is often a norm when engine is stone cold.

If this level drops or bottle becomes empty it’s using water (engine area ) or loosing it somewhere, leak/ radiator or it’s pushing it out through this expansion bottle,, usually because it’s been filled up to high.
A good idea at this point would be to check n/s or passenger footwell inside the car around the bulkhead so behind the battery. The heater box is mounted there so try to discount any wetness inside the car there. It’s unlikely but worth checking.

[NMNeil]

Mark-ixql7 said:

Hi all

I just picked up a chimp a couple of days ago. The previous owner had mentioned the coolant level always looks low in the expansion tank but it doesn't overheat. It was a 5 hour drive home, and he appears to be correct in that according to the temp gauge, it never went above 80c iirc.

I topped it up to half way yesterday and did about maybe 70 miles, and it was back to the bottom of the tank but again wasn't overheating. I checked the swirl pot and that's to the brim (and looking cruddy... First job!).

Seems a bit weird. I can't see any obvious leaks and once it's reached near the bottom it doesn't seem to budge from there. Normal, or any ideas what I should be checking here??

Cheers

If it's not leaking there are very few places the coolant can go.
And as you have a 'cruddy' swirl pot I'd start with one of these.
https://www.harborfreight.com/combustion-leak-dete...

[jimed]

I had an annoying slow leak on the Griff even though it had a recored rad and silicon hoses fitted. There was no sign of where the coolant was going but after some very close examination we found there were very small leaks from between some of the hoses and the pipes they were on, even though the clips had been tightened. In the end we fitted a second clip (next to the one already fitted) to many of the hoses and problem solved. Heath (x works) thinks this is something to do with the hoses being two ply (?) and fairly soft but it has sorted it. This might not be relevant for your problem but thought it was worth mentioning.

[Classic Chim]

jimed said:

I had an annoying slow leak on the Griff even though it had a recored rad and silicon hoses fitted. There was no sign of where the coolant was going but after some very close examination we found there were very small leaks from between some of the hoses and the pipes they were on, even though the clips had been tightened. In the end we fitted a second clip (next to the one already fitted) to many of the hoses and problem solved. Heath (x works) thinks this is something to do with the hoses being two ply (?) and fairly soft but it has sorted it. This might not be relevant for your problem but thought it was worth mentioning.

I’ve had occasion to consider if air gets dragged in via loose or newly fitted hoses. After a time corrosion/ anti freeze often forms on the pipe the hose is fitted to which then helps to seal it. It can sometimes be a right fight pulling off a long time sealed hose which then shows corrosion around its sealing point. A build up of anti freeze possibly creating the seal. Corrosion is bad though so any imperfections in especially the alloy parts will then encourage either loss of water or indeed draw air in, or both.
Best when changing hoses is to re face spouts with some fine wet and dry before this corrosion starts.
I fitted Powers branded TVR RV8 silicone hoses many years ago and never had a leak but after about 8 years corrosion had started forming on things like the swirl pot spout under the hose and jubilee clip as when I removed engine etc for body off work I noticed it. Only just forming but shows some dampness often gets right upto the clip most likely when it’s under pressure. I shortened the length of the swirl pot hose to show more alloy and hense less chance the alloy will rot as I often polish it I’ve seen that hose often pushed almost upto the body of the swirl pot and thought that’s just creating more area that’s going to rot under the hose!
As the years go by these things matter.

I think the link above to a test kit is very good advice at this point.

[Mark-ixql7]

Sounds like nothing to worry too much about then which is a bit of a relief 🙂 I've been out and about in it a couple of times since and it's not overheated or anything so I'll just look at getting the coolant changed when it's parked up for winter!

Thanks to all for the replies! No doubt I'll be about asking more questions at some point, going to try and get myself a copy of the Bible though which will probably answer a lot of stuff!

[Classic Chim]

If the swirl pot has crud floating about in it I’d be draining and flushing the system entirely with a high pressure hose.
Doing a 50/50 mix with new antifreeze and see what happens after this coolant change.

A good tip to establish how well the cooling system is operating in these cars is to listen for when your fans come on and off especially when in traffic or cars running stationary.
Unless you are in extreme heat, whilst moving along the fans should stay off.
They should only really come on after prolonged hard driving or driving slowly.
The tip is the fans should come on then fairly quickly go off. If they are constantly staying on you have a problem with your cooling system.

Keep an eye and ear out for the fans operation, the off being the important bit as if that’s happening theoretically the waters not getting above 92d which is when the fans should kick in.
I have an alloy rad and using a computer to monitor the engines coolant temp fans kick in at 91/92 and off again at 85 which can take a matter of only 10-20-30 seconds to achieve with fans on even with car stationary.
It’s very efficient if operating correctly.
My gauge often creeps up and up until 100 if subjected to prolonged slow periods of driving made much worse if sitting in traffic.
This constantly led me to fear water temps were too high until we did this test using a computer and a car running stationary for 40 minutes!
The gauge creeping up is often caused by heat soak effecting the reading and nothing to do with coolant temp at all.
The conclusion has to be as long as your fans go on/ off and cycle this way then your engines temps are under control.

Never leave it to hope and keep your ears open is the best advice

Edited by Classic Chim on Wednesday 19th October 07:33

[pits]

When you say crud, what do you mean? What coolant is being run in there at the moment? It should only be blue or green glycol based only, if it is orange you're not going to be far from potential leaks, OAT based or orange coolant will eat your system away, especially if you are running a copper radiator.

[Peter Thompson]

I had a similar problem - coolant loss, not overheating. Turned out to be a leak from the unused water port at the rear of the nearside cylinder head, which is blanked by the inlet manifold. 100% cured by fitting a new valley gasket.

[Mark-ixql7]

I'll keep an ear out for the fans kicking in on a longer run, ta. I've heard them starting and stopping in start/stop traffic and the gauge on the dash has never gone above half way. This does have an emerald ECU and I've now downloaded the software so I can monitor properly which is nice - I suppose I could actually do a data log of coolant temperature even!

As for Crud... It looked brown and rusty in the swirl pot. I've just done an oil change this morning and am in the process of giving it a good flush through of the coolant. When drained it was clearly the pink coolant, but it was kinda rusty orange tinted. The previous owner bought the car from str8six, and it had allegedly had a coolant change by them before he picked it up according to the paper work! Maybe whoever changed it before had used the pink stuff and str8six didn't want to flush it out I guess 😣

I already had some blue stuff (comma xstream g48) to put in once I've flushed all the current stuff out and it's running clear... I'm pulling the bottom hose, refilling, running to get it up to temp and get the thermostat open (mostly because I don't actually know where the thermostat is on this yet lol), letting it cool down, rinse and repeat...

[Classic Chim]

Follow the hose from your swirl pot back towards engine and it connects to your thermostat housing.

[Mark-ixql7]

Gotcha, thank you!! Took it off this morning and ran a hosepipe through that hose for a while, then through the swirl pot for a while. Seems like it's running pretty clear. May as well replace the thermostat while I'm at it now I guess!