Water coolant loss

T

TwinPlenum3500S

New Member
I am losing on average 1/2 litre of coolant a day. Top up, allow to run in case air in system, filled to about 1 inch from neck, then next day check and same problem.

Had a wep from top hose where Kenlowe was fitted, rectified with silicone sleeve, same problem. I cannot see any leaks, all hoses are brand new, but appears to chuck water out of overflow when walm.

I am running a standard P6 V8 rad with an SD1 engine, but I cannot se as this would make any difference to water loss. I am considering putting in an ally rad with additional cores to increase water capacity, but am totally confused as to the reason for this.

Engine runs really really well .... headgasket problems?? I canot see it, but please advise????
P6 rad not up to job with SD1 injection engine??
Top hose sits marginally higher than rad, are all P6's like this or jsut mine due to conversion?
Anything to do with thermostat?

Additionally purely out of interest, where does temp guage needle sit on ordinary P6 V8s when running? Did 140 miles in car yesterday and on motorway, sat bang in middle of green. When off m/way in traffic creeps up to 2/3 on green and Kenlowe kicks in...... this I feel is attributed to water loss.

Any ideas you V8 buffs :idea: :D
 
My initial thought is a head gasket problem. You can have this checked at a garage. they will test the coolant for carbon monoxide. If it is there, you have found your problem.

The increase in pressure caused by the gasket failure results in the coolant being forced out via the overflow.

Now it could also be something as simple as a radiator cap that is not sealing properly, so try fitting a new one first, and if no joy then look to the gasket problem.

The position where the temp needle sits is fine, and quite normal for the conditions you describe.

The standard P6B radiator is a dual core unit. Fitting a triple core will certainly increase coolant capacity and lower the normal operating temperature.

Try the radiator cap first, then have the coolant tested for CO.

Best of luck,
Ron.
 
I don't think you are necessarily actually losing coolant. All P6b's have a tendency to run the coolant at a level where you can just see the cores from the radiator filler kneck. No amount of topping up changes this. But I thought you had an SD1 rad? If not then you will definitely want to increase the capacity of your radiator. There are two possible routes. Have the existing rad recored with a three row core, or use one of Alan Classeparts aluminium rads. Either way get a standard modern radiator temperature switch let into the header tank to control the Kenlowe!

Fitting a header tank is a definite improvement and guarantees you have all the cores covered at all times. There's no particular right way to do this but an SD1 plastic tank will fit nicely at several points in the engine bay.

Chris
 
Sorry to disagree Chris but if he has to keep topping it up,he is loosing coolant somewhere!!
I had loss I could not find for ages!
Try dis-connecting and by-passing your heater rad,"you dont need it this weather" and see if that cures it!
When they leak it can be a real swine to diagnose,as water can drip onto the exhaust ,and it leaves no obvious signs!
You could bung in a bottle of rad weld and see what happens,but that wont tell you where the leak is!
Temp guage is about spot on for a p6 and then goes up slightly in traffic then the kenlowe cuts in!
Top hose does sit slightly higher than the rad,I normally top it up on some ramps to eliminate the air bubble that can occur.
Fitting an expansion tank is a handy measure but wont cure the leak!
These V8's can have water loss,pressurisation via cyl head issues but can go on for ages like it,they are a really tough lump!
You could always just pop a new pair of headgaskets on one weekend!
 
Thanks for the replies. The rad cap is brand new, so I would assume it is ok.

I will do a compressin test at weekend. Would you argue composite headgaskets are the way forward .... do you lose much performance with these, as they lower the compression by 0.5-0.7.

It is a P6 rad as SD1 is too wide to fit ... If head gaskets are OK ill buy a thicker ally one.

If it is headgasket problems, what are the symptoms in everyday running of car?

Thanks again.
 
Hello TP,

Composite head gaskets certainly provide far greater sealing between the head and block deck compared to the pressed metal ones, but as you noted the compression ratio will typically fall by 0.6 or so.

If you choose this option, then fitting a composite inlet manifold gasket is also necessary so as to keep all parts in their correct relative postion.

Composite head gaskets being thicker will also require you to check and adjust your lifter pre load as is necessary to keep it within spec. Placing shims of the appropriate thickness beneath the rocker shaft pedastals will do the job.

If you are driving everyday, then a much harder than usual top radiator hose is common, thus the reason the system is overly pressurised with coolant leaving the system via the overflow. Coolant could also flow across and enter the cylinder closest to the point of gasket failure, which would be rather a worry.

Coolant flows from the block into the each cylinder head adjacent to cylinders 7 and 8. There is a bleed hole only at the front of the block deck adjacent to cylinders 1 and 2.

When you run the engine when cold with the radiator cap off, can you smell exhaust fumes if you place your face near the open radiator?

Ron.
 
You could whip out the plugs and look in to the cylinders to see if there is any water sitting overnight. If it is clear then you may still have a HGF, do you have access to a gas tester you could check the coolant when running for signs of loss.

Colin
 
TwinPlenum3500S said:
Engine runs really really well .... headgasket problems?? I canot see it, but please advise????
P6 rad not up to job with SD1 injection engine??
Top hose sits marginally higher than rad, are all P6's like this or jsut mine due to conversion?
Anything to do with thermostat?

Additionally purely out of interest, where does temp guage needle sit on ordinary P6 V8s when running? Did 140 miles in car yesterday and on motorway, sat bang in middle of green. When off m/way in traffic creeps up to 2/3 on green and Kenlowe kicks in...... this I feel is attributed to water loss.

Any ideas you V8 buffs :idea: :D
Click to expand...

My car (Stage 1, 4L unit) did exactly the same.

I run an 82C thermostat but it didn't come with the little jiggle pin so I drilled a small hole at 12 o'clock to alleviate air blockage problems. (Yes you can do it in the morning if you like :) )

Mine sits between the 8 and the 5 on the temp gauge when running around, but quickly rises when in town, in traffic, on a hot day.

I fiited an SD1 expansion tank to the overflow pipe on the offside of the rad, then fitted a flat rad cap. I use a standard P6 rad cap on the expansion tank. I have also fitted a 14" blower fan in front of the rad connected up to a kenlowe actuator, but have just bought a spare heated rear window switch which I will connect it to as well so that I can turn it on manually if I know there is going to be a problem.

The level in the expansion tank can rise as much as 2" when hot, but will return to the original level when cold. This did solve my rad problem as the rad is always topped up fully now.

In my opinion, the P6B cooling system is not up the job of a tuned engine, being borderline with a standard unit.

I am also looking at other ways of lowering under bonnet temperatures such as (this may be controversial) wrapping the manifolds, fitting thermal blocks between the carb and engine (won't drop under bonnet temp but will help with fuel evaporation), and maybe raising the rear of the bonnet slightly.
 
Thanks for that. Glad I am not alone. I am going to put a water bottle to the overflow this afternoon and take it for a blast later and see what happens.

I would be keen to see how you fitted an SD1 expansion tank. If my bottle fills up, then I will go the thermostat route and at worst ways a compressino test.

Thanks ever so for all the advice.
 
TwinPlenum3500S said:
I would be keen to see how you fitted an SD1 expansion tank. If my bottle fills up, then I will go the thermostat route and at worst ways a compressino test.
Click to expand...

I just bolted it to the inner wing like this viewtopic.php?f=21&t=4843&start=75#p34124

I took the overflow pipe off and connected a short hose from the outlet to the expansion tank, then put the original P6 rad pressure cap onto the expansion tank. I put the overflow pipe onto the expansion tank.

The cap on the rad is now flat on the inside with no spring, just a flat seal across the top. The new hose and expansion tank is therefore pressurised with the rest of the system and allows any expansion to take place without interference. There are some electrical contacts on there to warn me of low level but I haven't got around to wiring this up yet.
 
You may just be losing the same coolant every time you're filling it up, because you're not leaving enough of an air gap to allow for expansion in the system. Top up with the engine running at about 2000rpm, to a level about 2" below the neck, fitting the cap while the engine is revving.

Out of interest, if you didn't top up after losing the first 1/2 litre, would you lose the same amount next Day?

Get hold of a pressure tester and pump the system up to 15psi and cure any leaks you find, and test the cap at the same time. Then let the tester pressure down to 5-7psi and run the engine giving it a good few revs, and see if the pressure rises and falls with the revs. A fall is what you should see, a rise could be head gasket.

If it is head gasket you can get a misfire when starting up after the engine has been left with the cooling system under pressure.

Most cases of "head gaskets" turn out to be something else altogether.
 
SydneyRoverP6B said:
Composite head gaskets being thicker will also require you to check and adjust your lifter pre load as is necessary to keep it within spec. Placing shims of the appropriate thickness beneath the rocker shaft pedastals will do the job.

Ron.
Click to expand...

If you fit composite gaskets, then the last thing you will need is the shims under the rocker posts, they are only needed when you lower the relative position of the head by skimming too much, or cutting the valve seats in too far, when fitting composite gaskets to an otherwise standard engine, you are actually going the other way and raising the head, so you would be needing to skim material off the bottom of the posts if you needed to do anything at all.
 
harveyp6 said:
Out of interest, if you didn't top up after losing the first 1/2 litre, would you lose the same amount next Day?
Click to expand...

I was going to ask that. Does the car over heat easily? I'm with Chris. Mine although a 4 pot, will loose about the same over a couple of days if I fill it right up to the neck, it's just normal expansion. I check about every four weeks and does need a little top up but the engine never over heats. It's what we all had to do many moons ago irrespective of make of car before they started to fit expansion bottles. I do have a £5 one in the garage to fit at some point, just not got round to it as she's running sweet at the mo, although does get a bit hot for my liking in sub 5mph traffic.

I agree with others that the P6 cooling is a little week and can't cope with any extra power. Possibly the only design flaw? ;) Must be something to do with the front of the car as it happens on all the engines.
 
My old V8 has a weepy radiator solder that I've never got around to sorting out, which translates to regular top-ups. Doing it correctly I follow the instruction manual: Start car with a coolish engine and rad cap off. Let idle until warm. When coolant starts to froth and squirt out the top, set idle to 1200-1500 rpm and wait for the thermostat to open, at which point coolant level drops off into the rad and you top up with some more tepid antifreeze (around three more pints I believe) mix until full. I usually rev it up to 2000 to get it 'all' in, then put the cap on. The system will shed excess and be otherwise nice and full and (theoretically) correctly pressurised.

Unless you're losing coolant onto exhaust/hot surfaces you should inside the car (thru the vents) be able to smell any leaks in the engine bay not coming out of the overflow hose and onto the road. Try your thermostat, isn't is sensible that if it doesn't open up, half the coolant can overheat and not correctly pass through the rad, but instead blow out through the cap? Does the level dip and the coolant swirl around in the filler neck when you rev the engine with the cap off? If not, maybe you have a dud water pump?
 
Hello Harvey,

Thanks for correcting my mistake regarding composite head gaskets and lifter pre load.

That is what happens when I type without thinking carefully about what I am writing.. :oops:

I apologise for providing misleading information.

Ron.
 
Plastic bottle fills up from overflow ..... I am now firmly of a mind that the P6 rad is not up to the job of cooling the Vitesse engine. I am going to have a measure up and order a bespoke 3 core ally rad and an SD1 expansion tank along with my Kenlowe.

I am thinking a compression test might be an idea too .. see how I go for time.
 
What about a cylinder leakage test ? See if it bubbles up in the radiator

Surprisingly no one has commented on my suggestion of Redline water wetter
 
I have some bottles of Redline at home - I'm saving them for the 4.6..... The theory is sound, should work in practice too.

Chris
 
Had car up on ramp today ... weeping coolant from head on either side ..... Ill keep it topped up and then have heads off. Composite head gaskets and valle gasket ..... also will drop in my new mild road cam, new lifters, new timing chain etc ... importantly will have opportunity to properly clean everything up, paint and detail.

Then ill get a header tank and watch my temp. guage with anticiapation ..... I feel tragic expense looming :cry: :cry:
 
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