VX coolant problems

[Jon Stewart]

I've had a cooling issue for the past year and am now becoming slightly frustrated

 

At the beginning of last year the car began spitting coolant out of the expansion cap. The system was bled several times and all seemed OK until a Cadwell trackday last year when lots of coolant was blown out and overheating occurred.

 

The HG subsequently needed replacement and the head skimmed. This was put down to a blockage in the restrictor to the expansion tank.

 

Since then i've had a few problems chasing small leaks namely fan switch and silicon hoses which replaced the rubber as a precaution.

 

The car has been running faultlessly for a while now on the until i noticed a puddle of coolant after a blat on Sunday. This was nowhere near as much as pre-HG replacement quantity which would spray you when moving, but seems to correspond with the use of more revs (8000+).

 

I don't know whether my previous problems were due to the HG failure or a different problem which still lingers.

 

I have done searches on Blatchat and have seen a coolant mod mentioned which i guess is something like here

 

Should i try a swirl pot or can anyone advise as to what my next step should be?

 

Many thanks

 

Jon

 

 

[Anthony]

Hi Jon,

 

Hope you are well.

 

Is it worth doing a pressure test to make sure there is no cylinder head leakage, this would at least put your mind at rest that the combustion chamber is sound and not pressurising the cooling system.

 

After that, its down to chasing minor leakage points and bleeding the system.

 

That being said, I had a small drip, which ended up being about the size of a penny on the garage floor, where there was not one before going to have the car flat floored. It has kept me up at night.

[F355GTS]

Jon

 

It sounds all too familiar i am afraid, if you are getting over expansion and hterefore coolant leakage fro mthe cap then air is getting into the system.

 

In the case of 'only with higher revs' I have direct experience and sadly in my case it was failure of the Head Gasket seal allowing compression gasses into the coolant, best check to do is a Hydrocarbons check on the coolant, you may have to rev the engine to replicate the fault.

 

FWIW I have two engines currently, one is perfect but the other shows exactly your symptoms so it excludes all the external factors such as rad, thermostat, expansion tank, pipe routing etc

 

I have a Hydrocarbons tester if you are nearby

 

Mark

[Jon Stewart]

Hi Anthony,

 

Hope the cars going well - the 7 Workshop isn't the same since it left

 

Is the pressure test you refer to the kit that pressures through the cap? If so i can borrow one from work, although from memory Chris did one before the Head gasket change and another since when i had the cage fitted. That's when the leaking fan switch was picked up.

 

Mark,

 

Thanks for the offer - again i think i can borrow one from the workshop at work. My first thought was the to re-bleed the system and try again but it feels like i've been here before and i'm only avoiding the inevitable. I have to say i'd be a bit miffed as i'ts probably done less than 500 miles since the last HG replacement and i was religous about running it regularly over the winter. I can stop feeling smug about having a VX over a K now 😬

 

My July 'ring trip is now beginning to look doubtful ☹️

 

Thanks for the replies.

 

Jon

 

 

 

 

 

 

 

[F355GTS]

Jon

 

my first failure of this type was, I was told, because the Head had been welded and this area was expanding/ contracting at a different rate. Not sure that was really the case as a completely new setup has shown the same problems, I run 2 Engines and one is fine the other is not so therefore it's definitely Engine related

 

Would have thought you could get it sorted very quickly though, easily to meet your Ring trip

 

Mark

[Paul Deslandes]

are you jacking the front of the car up as high as possible when bleeding the cooling system to make sure you get all of the air out?

 

 

[Paul Gibb]

Jon, Agree with all the above and have experience of most potential problems and solutions . This is not an uncommon problem with high rpm Vx's. The self bleeding top rad hose swirl pot is a quick & cost effective mod that I use & would recommend trying early (as copied from Nick D's big Vx and used by several other Vx owners) .

 

L7 FUN

[combine]

Yep , I get hissing from coolant cap when coming back from a blat and switching off in garage , no overheating problems and little coolant loss but maybe it gets worse ..... ?

[Jon Stewart]

Thanks all,

 

I have been bleeding it jacked-up on a sloping drive (back wheels chocked) but personally didn't do it last time. I think i'll get the HG checked out and try the top hose mod. Do i get this from the link above?

 

I was reluctant to go the Nurburgring again without proper a shakedown. My last two trips were cut short with a fuel pump that wasn't up to the job so an American V8 pump was installed. I was looking forward to testing this at Cadwell but ended up with a coolant shower and a new HG instead Looks like i need to pull my finger out.

 

Jon

 

Edited by - Jon Stewart on 9 May 2007 09:06:02

[Bio]

Hi Joh

I run a VX 2.0 injection and had similar problems when useing the flat Rover expansion tank. Always leaked from th cap after a good run.

Just changed to a lager round VX tank from a Cavalier and mounted it drivers side or cross section with new brackets.

Larger capacity, better preassure cap, and mounted higher (fluid level now above top of rad)

Worked so far evn after a 100 mile run at high revs.

Regards John

[Mick Day]

Jon

 

Indeed the Swilrlpot is the way to go. Note that the design for a K series will vary from the Vx as the hose angles are different. Get rid of the Rover header tank & get a swirlpot with a proper 15 psi rad cap.

 

Mick

[ECR]

In order to fit my Reverie airbox to my VX 16V I had to relocate the flat rover header tank (the new air filter sits just there). I have mounted it high up on the scuttle and so far this has eliminated all "bleeding" from the tank. My cam cover does not need washing after every spirited run now. If you don't want the expense of a swirl pot, relocation might work for you too.

[Anthony]

Hi Jon, I will let you know after Pau 😬

 

Hydrocarbon tester as F355GTS would be great start

 

Anthony

 

Car is nearly ready, but I have be saying that for at least a year :-)

 

 

 

[Foxy Smith]

ECR any chance of a photo of your expansion tank mounted on scuttle?

 

Thanks

 

Alan

[ECR]

Sure ...

Mail me and I will send by return.

 

 

Ex Chairman Roger

[Jon Stewart]

I have now made a few modifications but the system is still pressurising although i'm no longer been sprayed with coolant.

I bought a block tester kit which isn't showing head gasket failure.

There was a small leak from the thermostat bleed screw and after a few attempts was eventually sealed using PTFE tape (i don't know if this is right or not 😳)

The header tank has been replaced and is now the highest point in the system on the scuttle.

I had the radiator tested and it failed miserably. This has now been replaced and after a bit of leakage from the fan switch now seems to be sealed.

At this point i was getting quite hopeful but after some more testing at the weekend the system is still pressurising. 🙆🏻 The rad hoses were hard after turning off which i thought might have shown up any leaks in the system but i couldn't find anything. Air escaped from the expansion tank when i released the cap and i bled some from the top of the rad but it's still pressurising.

I ran the car up to temperature with the cap off last night to do another hydrocarbons test and as the stat was opening coolant came out of the tank and the level then dropped right down which suggested to me more air in the system although the test was again negative.

 

I have a few qeneral questions if anyone could be so kind

What is the correct procedure for bleeding the sytem now the header tank is at the high point? (I haven't used the thermostat bleed screw since i had so much trouble trying to seal it before).

When using the block tester kit last night i revved the engine quite hard but not for long. How sensitive are these kits as the previous HG failure was i believe detected at idle?

Do i need to seal the rad bleed screws or anything else for that matter?

Is there anything obvious i'm not doing correctly?

 

Thanks again,

 

Jon

 

 

 

 

 

[I reply to every thread]

Does it keep blowing out water indefinitely? When I purge & refill my system it will blow out something on the first few runs but then stabilise.

[Jon Stewart]

It hasn't been blowing any coolant out since the changes but has been remaining pressurised after cooling down .

I was concerned that it was still drawing air in or am i worrying unduly 🤔

 

Thanks

 

Jon