Cooling system - Coolant loss & head gasket.

[MoonlightVR6 10]

I suspect my VR6 has a duff head gasket or a leak somewhere but I am completely baffled as to the cause, location etc...

 

It has been loosing Coolant but more than I'd expect it to consume just driving about. Eg I work about 7 miles away, but with traffic it takes about 45-1hr to get there, each way.

Say over 2 days, so about 4 hrs of running, it has gone down to about halfway between the min level and bottom or expander - way below min level. When topping back up its about 1/3 to 1/2 of a litre, so a fair bit. I have to do this like 2-3 times a week.

 

Initially I thought head gasket, but I do not have the white mayo on the oil cap or in the coolant expander or oil dip stick? Hmmm

When started up its fairly smokey until it heats up, this is a whitey-greyish smoke, I'd say more white. When hot it looks about normal, not really smokey at all.

When hot it sits about 92-94 on the gauge, I have noticed in the last week or so that in gridlock it goes upto about 97-99, but when I move off it quickly goes back down to normal'ish 92 - 94, If I was on motorway it goes down even further maybe to 75-80ish.

 

It hasn't really been driving differently so I thought it could be leaking from somewhere else within the cooling system, a pipe or join...

 

As the system hasn't been flushed for a while there is like a rusty sediment on the sides of the expander and I assume in the coolant pipes. I'd like to flush this out but for the time being it makes it easy to identify any leaks, as once dried you can see the rust marks that was in the fluid...

 

The expander seems to get wet around where its sealed together (around the circumference), is this possible to split/break back into 2 parts, both the top and bottom? I can see its been getting pushed out of that little air release valve on the wheel arch side of the expander and it has a rust trail going down to that halfway rim and then it goes all around the rim of the expander, then dripping down onto the cables and body of the car below. So its either coming out of the molded together middle rim bit (possibly) and that air release valve deffo, I know, kill me! I cant figure out the air release thing as the coolant is never that high up, even when hot. and esp when its drained down below the min mark???

 

Where the heater matrix was bypassed and the pipes have been joined, it sort of sits above what I think is the steering pump, this was getting wet and I thought it was a coolant leak on one of these joins as I could see the rusty powder on the pump once it had dried. I jubileed this off and it hasn't really been wet looking since, but is still loosing coolant from somewhere.

 

Could the water pumps be knackered/leaking? I think I can hear the one near the spark plug distributer thing come on when the ignition goes live. I am not sure about the one near the air filter... Can I test this one somehow?

 

To flush the cooling system can I jubilee clip a garden hose to the rad coolant tube and just let it run through the entire engine for 10 mins, while massaging the tubes to fee up all that rust **** and get it out. - There isn't any valves etc in the cooling system that this could damage is there, or even the pumps?

 

Is there any other Tests where I can test for the head gasket having gone? Or any other places which are prone to leaking coolant?

 

 

Pls help!

[Sean_Jaymo 0]

Normally a pin hole leak in my experience. The problem comes in trying to find any evidence of this pinhole as they sometimes only get bad enough to leak under the higher pressure of high temps.

[Stonejag 10]

Is there high pressure in the water system when running - pipes inflated? Head gasket doesn't always mean oil leaks out into coolant, you can get a piston leaking combustion gases into the coolant instead.

 

The coolant transfer pipe ('crack pipe') across the front of the engine is always worth a check, they're called that because they're always cracked! You'll probably find one end of it snaps off as you remove it from the left side of the block next to the main water pump so don't fiddle without a spare to hand. To be honest I'd start by replacing the whole thermostat housing (3 parts), thermostat and crack pipe - making sure to get all remnants of sealant and pipe out of the crack pipe area - and try again. There are two or three senders in the thermostat housing held in by metal or plastic clips, the o-rings on these can also dry out and leak sometimes. I've also had good results with K-Seal, stopped a couple of nasty leaks for a good few months while I sorted out other things...

 

The expansion tank doesn't split apart (don't try!) - that lip's just where water collects when it exits the pressure-relief vent on the side. Check for pinhole hose leaks when hot - also try leaving the car on some big sheets of cardboard after a good run and see where the marks appear, may help pin down the rough area.

 

Stone

Edited June 11, 2014 by Stonejag

[Roger Blassberg 0]

Another favourite location for a leak is the joint between the radiator and the top plastic elbow, held together by two bolts into captive nuts within the radiator top moulding. There is an O ring in there. Look down the battery side of the radiator for stains and rust. Be aware though that the captive nuts in the radiator may not be quite as captive as they should be - they may turn with the bolts in which case the only cure for a leak there is a new radiator.

Also check the radiator temperature sender further down on that side (big brass hexagon with an electrical connector attached to the back of it) . It is not done up very tightly and the fibre gasket can start to weep coolant.

 

Best wishes

 

RB

[MoonlightVR6 10]

Hi Guys, thanks for the pointers.

 

I do not know how to check for high pressure.

I did notice the yesterday after driving about a fair bit that when I turned off the engine the air release valve was letting air out slowly, or this could be a pinhole leak around the rim part. But some sort of gas was escaping from somewhere aroundn the expansion tank. I am not sure how you'd judge if the coolant pipes were expended, but they were pretty hard (not soft and plyable like when the engine is cold), and hot as hell to the touch. You cant squeeze them like when its cold, well maybe by like 1 or 2mm at most.

 

Funnily enough I also noticed that when I put the air fan on I got a very feint smell of coolant. I don't know if this is vapour coming out the air-release hole on the expansion tank and then getting sucked into the behind of the dashm, as thats in close proximity, so I thought it could be from that. It could also be remnamts from about 5 years ago when the heater matrix blew. I don't know if this helps identify anything.

 

@Stone jag, whats the proceedure to test if I am getting gasses in the coolant? Shoukld there be any other tell tale signs?

I will try the cardboard trick tonight and let you know the results.

 

I will inspect the radiator some more later on today.

[Sean_Jaymo 0]

The "gases" is just oxygen being compressed by the fluid expanding due to the increase in temperature.

 

The cap shouldn't let any air out until the temperature gets properly hot ie north of 115c. This I to stop the pipes rupturing due to the high air pressure in them. If the cap is letting air out at under 100c, then the cap is broken. Get a new one, they're not expensive.

 

The system pressurises to raise the boiling point of the coolant so that you can run the temperature at the level required for effective running of the engine.

[MoonlightVR6 10]

Does the cap have a seperate relief valve to the one on the tank itself (under that black cover thing with g14 or something written onit?)or does the cap and that valve on the side of expander work together?

[Sean_Jaymo 0]

That thing on the side is just a cover that tells you what coolant to use. It's printed on the side of modern expansion tanks.

 

The valve is part of the cap.

[Sean_Jaymo 0]

Under the black cover is a small tube that directs excess fluid, if it does boil over, in a safe direction to avoid things blowing up in your face if of open the bonnet at the wrong time!

[MoonlightVR6 10]

[ATTACH=CONFIG]78879[/ATTACH]

 

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the image of the rust patches on the pump, I think has been fixed with the jubilee.

 

The second image you can see where its coming out of the expansion tank. The rust shows the path of the fluid. Does this mean the cap has deffinatley broke?

[Sean_Jaymo 0]

I'd say so. New cap is blue I believe, don't quote me. Either way, cheap easy fix.

[MoonlightVR6 10]

Yes my current cap is blue too. I will deffo try and get a new one of these before anything else.

 

Is there any chance the cap could be ok and its actually the valve on the expansion tank thats dudd?

[Sean_Jaymo 0]

There is no valve in the expansion tank. It's a bottle with 2 wires for the level sensor, a hole in the bottom to feed into the coolant system and a pipe in the top for excess fluid to return through.

The pressure control is carried out by the cap. There's a pressure relief valve in the cap itself.

[MoonlightVR6 10]

Oh right I thought there was 2 one in the cap and one in the expansion tank (well 2 on the tank actually). I couldn't see how the cap would feed the excesss out into those two holes on the side, so just assumed there would be 2.

 

I have the cap on order so I will let you know the prognosis after its run with it on.

[Sean_Jaymo 0]

Once the pressure gets to a certain level, the inside centre of the cap will rise and allow excess fluid and or air out through the centre of the cap and up over the top of the bottle threads and into the gully around the top which feeds into the overflow. At least this is how the Mk4 bottle and cap I have works.

[maff 10]

I had problem like this a while back on my old green vr and was getting paranoid about head gaskets etc, a quick trip to tps and one blue cap later all was sorted, I had coolant being chucked out of the side of the expansion tank and the new cap solved this for me:-)

[MoonlightVR6 10]

I replaced the cap today and topped it up few mm past max before leaving work, got home and it had burned its way down to about an inch below the min marker, once cooled back down.

I couldn't see a trail of the fluid leaking out of the cap/valve so I think that sorted that but its still loosing a lot of coolant, at leat 1.5 litres over a 7mile(hour) drive, I cant see any other traces so I am sure its internal.

 

How can I tell is the headgasket has gone without seeing any mayo substance? I read somewhere about oil in the water and I cant really tell but it desn't have bubbles of oil sitting on the top or anything. I am sure when I opened the coolant cap I thought I smelt a faint waft of petrol for a couple of seconds? Could this be the sign that the gasses are getting into the water system from the block?

 

Whats my next step to diagnose a headgasket? Will it show up on the VW fault computer?

[Jim Bowen 1]

Mine was really hard to diagnose. Changed everything else so knew it couldn't be much else. Could still drive it fine but coolant loss was as you describe. Ended up swapping the engine as once old one was apart I could see it was head gasket. The only thing I did notice was one spark plug slightly cleaner than the others but was very slight.

 

Does it run lumpy at all in the mornings or after being stood for about 12hrs. I also got quite a bit of steam/white smoke out the exhaust when first started.

 

Rad top hose was getting really solid as well, after a drive.

[MoonlightVR6 10]

Ahh man, I think she is in a bad way.

 

@Jim. Mine sounds similar, It has been running a bit lumpy in the mornings for about a month, but not for much time - until about 80degrees. Prior to that it was just the coolant loss.

The last maybe 3 days, its been doing that 'lumpy, going too slow in this gear feeling'at low revs, maybe upto 2000-2500 revs, when it should be smooth, then past that point it ran smoother. Wierd, geting worse I reckon.

 

(I ruled out the cap today as it was leaking from there, didn't do much as far as I am aware as it was still loosing fluid, but not out the cap as the fluid trail under valve hole on the expansion tank was still clean.

 

Drove it carefully home from work, lost about litre - 1.5.

Later when I went to sainsburies (approx 2-2.5 miles) I topped it few mms past max before I left.

I got to the shop ok, albeit the lumpy low revs. Then came out and it wouldn't start to come home.

The ignition came on and the dash lit up but it wouldn't turnover, nothing. Then by the 3rd try (its always normally first go, within about a second) it sort of made a weird noise like it was about turnover but got stuck then suddenly it went bang, like a single heavy clunk/thud sort of sound, I thought utoh that wasn't good. Then tried it again, did the same thing after the thud i had the key still trying to start it and it was just sapping battery not even turning over (the dash lights were going dimmer, until ignition was released).

I did't know what to do, I dont have rac/aa and my phone was at home. I didn't want to get a ticket or towed away to pound at all either. I was a bit distraught if honest.

It wasn't turning over at all so I thought maybe its the starter siezed or something as the battery & oil were good, coolant low but drivable and it was running like less than 10 mins before.

I rolled it backwards about 3 inches and dropped the clutch, I dont even know it that would unsieze it? (haha I shouldn't laugh) Then it started when i tried it with the key. But it was pretty damn lumpy, and smoking like a trooper! Moorso than in the morning, and it was getting close to running temp from driving up there.

Limped it home, and shes in a coma outside. :-(

 

She's gunna need a bit of open heart surgery, I'm just praying she'll pull through and the same for my wallet.

[Jim Bowen 1]

The rough running on mine was the piston chamber slightly filling up with coolant. I'd check your plugs and turn it over by hand. Doesn't sound good tbh.

[MoonlightVR6 10]

I think the gasket must have finaly given way completley as I am almost cirtain there is some water in the oil now too.

What do you think, up until yesterday it was a golden brown/blacky and now its got a creamy tinge to it.

 

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:-(

[g0ldf1ng3r 14]

I think the gasket must have finaly given way completley as I am almost cirtain there is some water in the oil now too.

What do you think, up until yesterday it was a golden brown/blacky and now its got a creamy tinge to it.

 

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:-(

 

oh dear :( i think you have confirmed your worst thoughts with that pic. good luck!!

[MoonlightVR6 10]

Roughtly, whats the worst case scenario, will it need to be completely re-built?

[Jim Bowen 1]

With the thud noise and the fact it got stuck until you rolled it, i would think it at least need to checked out thoroughly rather than just changing the gasket.

 

Might have damage to a cylinder

[MoonlightVR6 10]

Do you think I should drain all the oil and coolant etc in the meantime? Can it mix further if its not used or will the damage be the same if its all left in there?