Coolant leak

[stever]

Appreciate any help to a proud new owner and driver of a 91 400SE, but no mechanic!
Coolant has recently started weeping/dribbling out from the pressure cap (next to the oil filler) all of a sudden. Have tried swapping the cap with the one on the expansion tank so can't believe both would suddenly fail. I have topped up the expansion tank several times, is it possible to perhaps get an air lock in the system?

Also what is the correct level for the coolant, the original owners handbook suggests the expansion tank should be full and the reservoir overflow bottle should be half full when cold. Is it possible to overfill the system? Grateful for any help! Thanks.

Steve

[streaky]

stever said:

Appreciate any help to a proud new owner and driver of a 91 400SE, but no mechanic! Coolant has recently started weeping/dribbling out from the pressure cap (next to the oil filler) all of a sudden. Have tried swapping the cap with the one on the expansion tank so can't believe both would suddenly fail. I have topped up the expansion tank several times, is it possible to perhaps get an air lock in the system? Also what is the correct level for the coolant, the original owners handbook suggests the expansion tank should be full and the reservoir overflow bottle should be half full when cold. Is it possible to overfill the system? Grateful for any help! Thanks. Steve

What's the temperature gauge reading? - Streaky

[wedg1e]

A pair of new caps is only about a fiver. Standard Quinton Hazell bits, FC53 and FC57 if I remember rightly.

Coolant normally finds its own level during a thrash by blowing off any excess!

Ian

[stever]

Gauge has been reading fine upto now around 80-85 creeping to 90 in traffic but the fan has cut in Ok.

Reason I question the owners handbook is that another ex wedge owner said he never bothered about the resevoir overflow bottle and just made sure the expansion tank was 3/4 full

[HeyAndy]

Don't swap the caps from the header to the swan neck. There'll be a heavy build up of pressure which will dump water very quickly out of the header tank.

I made that mistake the first time I had a TVR many years ago and got showered with scalding hot water with nasty burns to my face and forearms!!

Examine your hoses and the rad for a leak it'll be easy to fix. Replace the swan neck cap for a new one and check the thermostat to see if it opens as that may also be a possible cause.

[Planman350i]

I just fill the expansion bottle right up to the top of the yellow marker inside. I check it everytime from cold, but rarely needs topping up. I have to say that I never look at overfill bottle much.

[stever]

Thanks guys appreciate the help and advice.

I presume the "swan neck" is the cap adjacent to the oil filler cap, it's just that I would expect it to resemble a swan's neck but mine doesn't!

I'll try replacing the cap, and check the thermastat, the rad is OK and has recently ben re-cored.

Thanks to all.

[350zwelgje]

Had the same problem.
The fix for me was getting a new hose clamp on the small diameter hose just beneath the cap. Even with a new clamp it was difficult to stop the leak. And then I had my fix again..... without worries.
I know it is simple but sometimes you must have a break during TVR ownership.

Good luck,

Rob

[gerry attrick]

I had a similar problem with mine. Discovered that the fitting on the swans neck was bent, and did not allow the cap to seal properly. A few dabs of plastic steel followed by sanding with 280 W&D on a block did the job.
Best of luck.
Don

[HeyAndy]

I saw a thread in which I believe Steve Heath mentions that he fabricated the swan neck to accept a srew on cap on his SE available from most reputable central heating suppliers.

I think i'd be interested in doing the same thing if there was more info available.