coolant problems

[katanaman]

you either cleared some air or its throwing it out the tank. Don't let it go down or you will be back at square one with air in the system.

[ramon alban]

Went for a blat last night, probably about 15 miles.
Checked my coolant this morning and would you believe there is significantly LESS in the exp tank than when I started last night.

I don't get it, the last few times I check it when cold, it has risen every time. Now its on its way down.
Can anybody make any sense of this?...........please!!

Now you are getting there. As the engine cools the resultant drop in pressure sucks in some fluid, dont let it suck air, top it up go for another blat, and it will get better.

The last paragraph on the link may give you an easy solution.

Quote

Route the overflow pipe into a flat plastic bottle (0.5 - 1.0 litre) secured on the chassis rail below the tank to catch expelled fluid. As the engine cools, the resultant vacuum sucks fluid back into the system preventing continual topping up. Amazingly, filling the bottle automatically tops up the system as the engine cools & is completely safe as it is unnecessary to remove the pressure cap.

Unquote

http://www.vintagemodelairplane.com/pag ... ant01.html

[dave wj]

Went for a blat last night, probably about 15 miles.
Checked my coolant this morning and would you believe there is significantly LESS in the exp tank than when I started last night.

I don't get it, the last few times I check it when cold, it has risen every time. Now its on its way down.
Can anybody make any sense of this?...........please!!

Now you are getting there. As the engine cools the resultant drop in pressure sucks in some fluid, dont let it suck air, top it up go for another blat, and it will get better.

The last paragraph on the link may give you an easy solution.

Quote

Route the overflow pipe into a flat plastic bottle (0.5 - 1.0 litre) secured on the chassis rail below the tank to catch expelled fluid. As the engine cools, the resultant vacuum sucks fluid back into the system preventing continual topping up. Amazingly, filling the bottle automatically tops up the system as the engine cools & is completely safe as it is unnecessary to remove the pressure cap.

Unquote

http://www.vintagemodelairplane.com/pag ... ant01.html

Thanks Ramon,
Putting in a catch bottle sounds a good plan. My exp tank doesn't have a top hose above the pressure cap seal, its just below (routed to the top rad hose).
I guess what I need is an exp tank with the top small bore outlet situated on the atmosphere side of the pressure cap (identical to radiator set up) so that if water is expelled via the pressure cap I can route it down to the catch bottle as you suggest, rather than spraying out via the cap which is what could happen with my set up..

I had a look for one of these at the scrapper but I could only find the type that release pressure straight out of the cap.

Anybody any idea where I could get an exp tank that I can route to a catch bottle at a reasonable price. I've seen ally ones but in excess of £80.00 , a bit pricy for me, also ally has the disadvantage of me not being able to see what is going on.

Thanks again for your help.

Cheers

Dave

[ChrisJC]

I expect my expansion tank is about 1 litre. It's not very big.

Chris.

[dave wj]

I expect my expansion tank is about 1 litre. It's not very big.

Chris.

Many thanks,

Dave

[ian.stewart]

Catch can is a good Idea, even if you do not plumb it as a vacuum return, at least you will know how much water is coming out of the system. My feelings are you are possibly running a marginal system on the cooling side, with a exp tank that is too small, Lose a bit of water, not a problem but as the little losses accumulate into a larger loss the engine will boil.

[Paul B]

Catch can is a good Idea, even if you do not plumb it as a vacuum return, at least you will know how much water is coming out of the system. My feelings are you are possibly running a marginal system on the cooling side, with a exp tank that is too small, Lose a bit of water, not a problem but as the little losses accumulate into a larger loss the engine will boil.

I find it hard to believe that the water volume will expand over a litre merely from heating it up. My stock 3.5 raises the expansion tank level by a couple of teacup fulls from cold to boiling hot.
In fact before I fitted the expansion tank I had a small plastic bottle strapped to the side of the radiator but wasn't sure it was big enough and added the 1 litre expansion tank from some nameless prehistoric vehicle.

Dave, Have you tried running a water house directly into the radiator input to see if water gushes freely from the top of the block, (thermostat removed) just to make sure you don't have something silly like a slipped or incorrect gasket blocking a water passage?

[dave wj]

Catch can is a good Idea, even if you do not plumb it as a vacuum return, at least you will know how much water is coming out of the system. My feelings are you are possibly running a marginal system on the cooling side, with a exp tank that is too small, Lose a bit of water, not a problem but as the little losses accumulate into a larger loss the engine will boil.

I find it hard to believe that the water volume will expand over a litre merely from heating it up. My stock 3.5 raises the expansion tank level by a couple of teacup fulls from cold to boiling hot.
In fact before I fitted the expansion tank I had a small plastic bottle strapped to the side of the radiator but wasn't sure it was big enough and added the 1 litre expansion tank from some nameless prehistoric vehicle.

Dave, Have you tried running a water house directly into the radiator input to see if water gushes freely from the top of the block, (thermostat removed) just to make sure you don't have something silly like a slipped or incorrect gasket blocking a water passage?

Hence my concerns.

I've not tried running a hose into the top of the rad as you suggest. I would be amazed if the gasket had moved to such an extent or was incorrect as the engine was prepared by a highly respected RV8 engine supplier who claims to be the Guru of all things V8....then again who knows.

Thanks for your thoughts, it gives me another angle to consider.

Cheers

Dave

[dave wj]

Catch can is a good Idea, even if you do not plumb it as a vacuum return, at least you will know how much water is coming out of the system. My feelings are you are possibly running a marginal system on the cooling side, with a exp tank that is too small, Lose a bit of water, not a problem but as the little losses accumulate into a larger loss the engine will boil.

Thanks Ian,

Cooling especially in the rather cramped area under the kitcar bonnet is always problematical. Underbonnet heat is difficult to get rid of, so you are probably correct in your assumption that my cooling system may be marginal although I have been told by people in the know that my rad is well big enough and everything plumbed in correctly etc.

I have not yet blown coolant from the top of my exp tank (I feel this is only a matter of time) nor am I getting overheating, and as the confusion lies in the varying coolant levels Iam experiencing, I feel my first job is to increase the size of the exp tankand see what happens.

I've always assumed that the coolant should return to its original level once the engine cools, mine is all over the place, sometimes higher sometimes lower .

Anyway I really appreciate everybodys input, and reasuringly nobody has mentioned the dreaded cracked block syndrome that 4.6's seem prone too, so thats a relief.


Thanks guys

Dave

[ian.stewart]

If the dreaded block problem had manifersted its self, I think you would have notices either plumes of white smoke out of the exhaust, or a total inability to keep water in the rad.

[dave wj]

If the dreaded block problem had manifersted its self, I think you would have notices either plumes of white smoke out of the exhaust, or a total inability to keep water in the rad.

Hi Ian,

When the earlier symptoms of losing coolant for no apparent reason reared its ugly head, I did start to wonder if it was disappearing via the cylinders, especially bearing in mind I had a boil up earlier.
So when the coolant started to rise, again the reason not being obvious, I started to think emmission gases getting into the cooling system, so either cracked block or head gaskets.

I pulled the plugs to see if there is any sign of steam cleaning......all ok.
No sign of white smoke from the exhausts., so it looks ok.

Head gaskets failure? again cant't be sure as the hydrocarbon test didn't work for the reasons mentioned earlier.
I feel I need to get back to basics, firstly put a larger exp tank in. Get the front of the car jacked up and run it to see if there are any further airllocks released.
Thought about using some water wetter to aid the circulation and maybe help any stubborn air to shift.
If this doesn't help, then I guess I need to have a closer look at the gaskets.

Does this plan of action seem ok? I can't think of anything else to try.
I've taken on board what everybody has suggested and hopefully will sort it painlessly.

Thanks to all who have taken the trouble to help me, its very much appreciated.

Cheers for now

Dave

[ian.stewart]

Im trying to think of alternative ideas, as i run a totol loss system, and I lose a fair amount of water, before the engine finds its owm level, I can see why you need to run a expansion tank because of the level of your rad, are the caps you are using new?? and what pressure cap do you use? My cap is a STANT with a 22lbs releif, the advantage, as i see it is the more pressure the water is under, the higher the boiling point, and less of a problem of airation, I also use a wetting agent just to help things along.
one thing that you need to check is, does your pressure cap have a releif valve built in so the air can be sucked back into the system as the engine cools, I have seen pressure caps without this facility,this caused funny cooling problems to a friend of mine and eventually was found when the bottom hose was seen to be sucked flat when the engine was cold.
Ian

[dave wj]

Thanks Ian,

Yes my exp tank has a pressure cap with both the facility to expell as well as suck the air back in. The cap is new although I don't know the pressure rating. I used to have a 15lbs pressure cap on my rad which used to blow a small amount of coolant. I got rid of this and put a non pressure cap on.
The only pressure cap I have now is on the exp tank and as it has yet to blow the coolant out I suspect it is rated higher than 15lbs.

This is something I should test I guess. I think I'll go the same route as yourself with the water wetter, as you say to help things along.

All this will now have to wait as I am going on my hols for a week (complete with brolly and wellies )

Thanks for your thoughts and help. If you have any more ideas, please post and I'll have a look when I get back.

Cheers to everybody.

All the best

Dave.

[dave wj]

UPDATE:

Hi Guys,
Sorry about the delay in posting back,better late than never.....wrecked my back so the mods had to wait.
Anyway, I've fitted a larger expansion tank and put in water wetter and a higher pressure cap.
As I can now see through the tank (as opposed to my old ally one) I notice that the coolant rises a modest amount when hot. I'm still getting the varying heights of coolant when cooled off, but it would appear to be fairly constant ie dependant on whether I drive hard or just cruise the coolant when cold will either be higher than the original level or below, or very occasionally stay the same.
The good news is that Iam no longer blowing coolant out the cap.

Now here's the question based on the above:

Is it possible for some of the air in the expansion tank to move around the engine and thus affect the levels of coolant as outlined above? ie the air displaces the coolant from elsewhere into the exp tank...hence the higher level when cold?, then the other extreme.....finds its way back to the exp tank causing the level to seemingly drop?

Its the only logical thing I can think of.

Anybody had a similar thing?

Thanks for your thoughts

All the best

Dave

[Paul B]

UPDATE:

Hi Guys,
Sorry about the delay in posting back,better late than never.....wrecked my back so the mods had to wait.
Anyway, I've fitted a larger expansion tank and put in water wetter and a higher pressure cap.
As I can now see through the tank (as opposed to my old ally one) I notice that the coolant rises a modest amount when hot. I'm still getting the varying heights of coolant when cooled off, but it would appear to be fairly constant ie dependant on whether I drive hard or just cruise the coolant when cold will either be higher than the original level or below, or very occasionally stay the same.
The good news is that Iam no longer blowing coolant out the cap.

Now here's the question based on the above:

Is it possible for some of the air in the expansion tank to move around the engine and thus affect the levels of coolant as outlined above? ie the air displaces the coolant from elsewhere into the exp tank...hence the higher level when cold?, then the other extreme.....finds its way back to the exp tank causing the level to seemingly drop?

Its the only logical thing I can think of.

Anybody had a similar thing?

Thanks for your thoughts

All the best

Dave

No, unless your coolant level drops below the bottom of the expansion tank there is no way for the air to get 'down' to the engine. If anything the system should improve slowly as stray bubbles find their way into the expansion tank and get trapped above the coolant level.

I'm assuming your expansion tank is fed from the bottom, and never ever gets empty?

I have been told one way to get any bubbles out of the system is to cut the bottom off a plastic 2 litre Coke bottle and upend it into your rad cap neck, sealed with tape. Then fill the bottle with coolant so it is much higher than the rest of the system. Run the engine for a while and any bubbles that pass by the rad will shoot up into the Coke bottle and into the outside world. When you see no more bubbles you can take the bottle off and pop the rad cap on. Run the engine and water will expand into your expansion tank as normal. Check the level frequently while it warms up.

Also try jacking the front of the car up so bubbles move forward from any hidey places they can lodge in.