Vauxhall Owners Network Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
Hi!

First post :) but it may not be a happy one :(

Have a K plate '93 1800cc 8v Cav. It's done just over 135k with 4-5k added each year. It's due for annual service and MOT by the end of the month. Absolute cast iron build and reliability - owned since 15k and started every time!

I have a hunch it may be the early stages of HG failure with coolant escaping into the cylinder. I'm having dificulty in tracking down the cause.

There are no pools under the car overnight or if left running for 20 minutes or so.

I've recently been noticing a cooler than normal heater temperatuer in-car and a slight oil smell on startup.

I've been keeping an eye on coolant levels. Worryingly, it needs topping up almost every day - put 12 pints of water in last night with a top up of 5 pints of coolant tonight. Milage is about 20 a day.

I've noticed a white vapour trail from the exhaust but have put it down to the recent cold weather.

Expansion tank is clean with no white residue, oiliness or smell. The tank stays cold and half full for around 10 minutes. After that, the tank fills with hot water from the bottom and boils. Fan kicks in. There is a 'glugging' sound from within the rad and pipes.

The oil looks fine too on the dipstick with no water or residue.

I've not been giving it the berries due to the age of the car and it had its HG done at 80k with all the belts. To save tears I now change at 4500rpm max.

So, any ideas? I have a suspicion it may be coolant leaking from the water jacket via the HG into a cylinder, however the rate at which it's losing water gives me doubts. Could it be the water pump or something opening up under pressure or load?

Advice and guidance welcome.

Ta - WolvoCav
 

·
CavWeb's Oldguy
Joined
·
4,816 Posts
12 pints a day is a lot of water. If it was leaking thro the water pump or eslewhere there would be a big puddle at least under the car.

Only other places the water can go is into the oil or a cylinder. Looks like the head gasket to me.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #3
Thanks for the reply GREYDJ. Others are still welcome to give their opinions.

I'm going to keep my eye on the water levels over the next few days again and just see exactly how much is going out the back.

If it is the HG, I'm also worried that as it's been done before, the head may have warped. The guy who did the HG at 80k said that Cav heads can suffer from aluminium pitting.

If it does turn out to be the HG, I may go for a replacement gasket. If it's warped the head, I think skimming will be too much. How much do 8v lumps go for these days?

Ta - WolvoCav
 

·
Registered
Joined
·
144 Posts
I am sorry to say, but I too would bet on the HG. When they go, you do not always get water mixing with oil or oil mixing with the coolant.

Good luck with it
 

·
Registered
Joined
·
56 Posts
i had a similar problem once, i had a very small pin hole in the heater matrix,which i changed,but also found out that the water was escaping through a port in the hg, rather than just change the gasket i also got a second hand head as they do tend to warp,it was cheaper than having it skimmed,plus your up and running alot quicker.
 

·
Premium Member
Joined
·
1,163 Posts
Engine core plugs can go porus and leak under pressure too - often no sign ofe leak as it stops as the engine cools and any evidence of a leak evaporates on the hot engine.

Does sond ike the HG though. Might simply be that whoever did the last job didny tidy up the head/block and there was a slight errosion chanel left in the head or bits of old gasket left on the block.

Opening up the head t have a look will cost you nothing - you can then judge whether it's worth spending on a gasket set and new bolts.
 

·
VxOn's Nissan Advocate
Joined
·
1,324 Posts
definately sounds like head gasket, water could be going into the bores, rather tham the oil. 12 pints of water is rather alot
 

·
Registered
Joined
·
28 Posts
if it's not leaking out under the car then to use 12 pints in only 12 miles then it must be the head gasket. with that sort of quantity i would of thought the car would be going slower since water doesn't even have the octane level of tescos unleaded. mind you they use water injection on cars for more hp so it may just be evening out for the moment but i expect it will get a lot slower very quickly. if one cylinder is running a lot cooler than the others due to a water leak then it will cause uneven heat expansion of the head and cause the gasket to "go" quicker
in this weather most cars have a plume of smoke coming out of the back of them when cold. drive it a few miles untill she warms up to operating temp and then pull over and rev the engine and see if it is still smoking. if it is then the hg has gone. also check for leaks up the front now that it is warmed up.
if the pipes are glugging then there is definately air in them. you need to fill it up properly.
also if your rad cap is faulty it may be allowing it to blow out through there and it may not be opening up to take more water in through the expansion tank. go to a scrap yard and get another and change it. this could be the cause of all your problems since you have air in your system and it isn't taking any water from the expansion bottle.

all of these are good suggestions but 12 pints for 20 miles. that's one hell of a lot of water. it's time you stopped driving it and found the fault before you do any damage to the engine because it must be going somewhere and doing something unwanted.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #10
Thanks for all the replies.

Just checked on the coolant level this evening and it's at normal levels in the header tank. Nothing's been used over today's 20 miles. Now puzzled.

Going to take it out on a run for 20 minutes or so. Will report back later.

Ta - WolvoCav
 

·
Registered
Joined
·
13 Posts
Discussion Starter #11
OK, been for a drive and the plot thickens.

Took it easy for the first 10 minutes - urban traffic speeds of 4th & 5th gears @ 30-50mph. Pull over.
Checked the water level - fine.
Checked exhaust - no water vapour.
Expansion tank and feeder pipes cold. Rad pipes getting warm.

Had a blast for 5 minutes of 3rd, 4th and 5th gears @ 50-100mph. Pulls hard and smoothly with no lumps or flatspots through the rev range. Nothing feels out of the ordinary. Pull over.
Checked water level - fine, no coolant loss
Checked exhaust - no vapour.
Expansion tank and feeder pipes luke warm. Rad pipes hot.
Noticed in car heater was running quite cool.

Took it easy for another 5 minutes going back to home. Back at base.
Checked water level at end of journey - fine, no coolant loss.
Checked exhaust - no vapour.
Expansion tank and feeder pipes hot. Rad pipes hot.
No real change in temperature from in car heater.

As a final check, left the engine running for about a minute with the expansion cap off when until the expansion tank filled suddenly and began boiling and pusing out coolant. Rad fan didn't kick in.

Have now topped the system up with about 3 pints and will take a look on Sunday as to if any coolant has been used.

I swear I'm going crazy! :Arrgh: Part of me thinks something's up and the other is being all optimistic. Me thinks it might not be the HG after all. Argghhhh! I dunno!

Ta - WolvoCav
 

·
Registered
Joined
·
28 Posts
WolvoCav said:
OK, been for a drive and the plot thickens.

Took it easy for the first 10 minutes - urban traffic speeds of 4th & 5th gears @ 30-50mph. Pull over.
Checked the water level - fine.
Checked exhaust - no water vapour.
Expansion tank and feeder pipes cold. Rad pipes getting warm.

Had a blast for 5 minutes of 3rd, 4th and 5th gears @ 50-100mph. Pulls hard and smoothly with no lumps or flatspots through the rev range. Nothing feels out of the ordinary. Pull over.
Checked water level - fine, no coolant loss
Checked exhaust - no vapour.
Expansion tank and feeder pipes luke warm. Rad pipes hot.
Noticed in car heater was running quite cool.

Took it easy for another 5 minutes going back to home. Back at base.
Checked water level at end of journey - fine, no coolant loss.
Checked exhaust - no vapour.
Expansion tank and feeder pipes hot. Rad pipes hot.
No real change in temperature from in car heater.

As a final check, left the engine running for about a minute with the expansion cap off when until the expansion tank filled suddenly and began boiling and pusing out coolant. Rad fan didn't kick in.

Have now topped the system up with about 3 pints and will take a look on Sunday as to if any coolant has been used.

I swear I'm going crazy! :Arrgh: Part of me thinks something's up and the other is being all optimistic. Me thinks it might not be the HG after all. Argghhhh! I dunno!

Ta - WolvoCav
if there is no change in the cabin temp then it seems that either the valve that controls the water flow (hot/cold) isn't working or there is nothing but air in the heater matrix. this is common with a small leak because it is generally higher than the rest of the water system. find the valve and make sure it is open and when filling the engine with water give the pipes a squeeze to help bleed any air bubbles in the system. i would still consider changing the cap. never had a problem with the cooling on mine so i am not so familiar with the water system on the cavs. if the fan doesn't work then try unplugging the temp sensor screwed into the rad somewhere and shorting accross the wires to check if the electric fan works or not. don't forget to turn on the ignition. i might also be inclined to remove the thermostat just to check it and to aid the removal of air bubbles in the system. the car will be fine without it for a few days. when putting water into the car make sure the cabin heater controls are in the hot position. if in doubt of the valve then take it off and check manually (blow down it ).
i am amazed there is no vapour at all what with 12 pints for 20 miles. that is 13.3 miles to the gallon on water alone never mind the fuel. it must be going somewhere.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #13
Thanks for all the responses - most welcome.

Well, after much prodding, poking and fertting, I have to say that I am well convinced I don't have a problem with the HG.

I'm now equally sure that it was the headder tank cap not being on tight enough. Doh!

Admittidly the cap may have been too loose for some time. A good thrash could easily account for 12 pints on a single run.

Anyway, the caps on tight and no water has been lost since. Now I can face a more affordable service and MOT on Wednesday :bananasmi

Ta - WolvoCav
 
1 - 13 of 13 Posts
Top