Head gasket failure?

[Rob_the_Sparky]

I thought I was having problems bleeding the air out of the cooling system after changing the thermostat and hoses...bunt beginning to get worried about the head gasket, can any one advise?

I had noticed that every time I squeezed the top hose after driving the car and letting it cool down I got a little air out of the system. This seemed reasonable at first as this is the highest point in the system. However, it has been doing this for quite a while now and came to it today and the water level in the expansion tank was higher than normal by about 2inches!

Is this common n these V8s? Anything else that might be causing this?

All ideas welcome before taking the engine out...

Ta

Rob

[chris52]

Do you have any other problems ie overheating, lumpy running, Cooling system over pressuring, oil in water, water in oil etc etc of not I would guess you don't have an issue and it's just sorting itself out.
Chris

[Exige S]

With no other symptoms I doubt it's a head gasket issue, most probably you have a little air trapped in the system somewhere that's making it's way to the rad etc.

Have you tried screwing a funnel into the swirl pot, filling it then bleeding the air out via the blanked off throttle heater pipe? It's tucked down in front of the intake side of the plenum, it's the highest point in the system.

Hope that helps.

[Rob_the_Sparky]

Exige S said:

With no other symptoms I doubt it's a head gasket issue, most probably you have a little air trapped in the system somewhere that's making it's way to the rad etc.

Have you tried screwing a funnel into the swirl pot, filling it then bleeding the air out via the blanked off throttle heater pipe? It's tucked down in front of the intake side of the plenum, it's the highest point in the system.

Hope that helps.

Oh, that is helpful. Rather than a funnel think I'll lift the expansion tank up high though, unbolt it, then lift it up as high as possible and hang it from the roof (found that the bonnet strut on a TVR is too weak!).

Cross fingers...

Rob

[TJC46]

There are a few ways of bleeding the cooling sysytem and some are more successful than others.
The following applies to my serp engine chim, with a seperate swirl pot and expansion tank.
I find a good way is to remove the top heater hose from the heater pipe [drivers side near the alternator]. This is the highest point anywhere in the system.
Stick a clear plastic funnel in the hose and, [on my chim ] i then fix this to the bonnet stay, so its easy to pour coolant into.
Now open the bleed screw on the rad and release any air until nothing but coolant comes out.
Next open the expansion bottle and pour coolant through the funnel stuck in the heater hose until all air is burbling out into the expansion bottle and the level of coolant in the expansion bottle starts to rise.
You may also at this point get some coolant coming out of the heater pipe where you removed the hose from. This is also a good sign, indicating that you have removed all the air from within the heater system.
Replace the hose on the heater pipe, check and adjust the level in the expansion bottle [on my chim its happy with about 40 to 50 mm only in the expansion bottle] and take her for a blast. Later when everything is cold check the expansion tank and top up if necessary.

Edited by TJC46 on Monday 13th August 20:45

[Rob_the_Sparky]

thanks for the input

[ESDavey]

I would also check around the expansion cap (Blue VW part number is 443121321)for signs of leaking coolent. My old cap was not holding pressure & was the incorrect part & oval !

http://www.pistonheads.co.uk/gassing/topic.asp?h=0...

Edited by ESDavey on Thursday 16th August 08:19

[TimJM]

I've had to replace my coolant three times in the 18 months (a combination of bad luck, radiators and stones) and each time I do it as below and haven't had any air lock issues. I'm not sure of the "correct" way as some people say not to run the car with the swirl pot cap off as this will draw in air but this is how I've done it and it has worked every time for me:

These instructions are starting with an empty system but should still be roughly right.

1) Take off the swirl pot cap, the expansion cap and loosen the brass rad bleed nut.
2) Fill the expansion tank just above half full (or keep adding coolant until it settles about half full).
3) Put a funnel in the the swirl pot - keep adding coolant until it stops going down.
4) By now coolant should be leaking out the rad bleed nut so tighten the nut up.
5) Check the expansion tank is still half full (or slightly more) and put the cap on.
6) Fill the funnel in the swirl pot to about half full and start the engine.
7) Make sure heaters are on hot and blowing.
8) Keep adding coolant to the swirl pot again (I assume it will go down once the water pump is operating) until it stops going down again.
9) Put the cap back on the swirl pot and turn off the engine.
10) Check if the expansion tank level has dropped and top back up until half full if necessary.
11) Let engine cool for 20 minutes or so and then check expansion tank again and top back to half full if necessary.
12) Put expansion cap back on, run engine - watch temp gauge like a hawk, check for any hose leaks and ensure fans kick in before 90deg (or where ever they used to kick in on your gauge).
13) Turn engine off, let cool and top expansion tank back up to half again if necessary.
14) Go for a longish drive (30 mins+) and take some spare coolant just in case. Make sure the fans cycle on and off a few times on the drive. If not summer/traffic just pull over a couple of times on the drive and idle until fans cut in.
15) Check the expansion tank again in the morning when proper cold and top up if necessary.

Good luck.