Coolant leak and trip to Silverstone

[JonRB]

Hi folks I think my Chimaera has a special sensor that detects when my step son goes to his Dad's and my partner & I can therefore enjoy the TVR together - because it always chooses those weekends to develop a problem! This time, just over a week after my infamous 3-week layup at Hawthorns due to overheating which turned out to be an otter switch, it was continuing problems with cooling. I noticed light blue slighty gloopy fluid dripping out from under the car in a slow steady drip. On investigating further I found my expansion tank to be empty. Water temperature had been fine on the trip out just before I noticed it, so I half-filled the expansion tank with water and went out for a local trip and watched the temperature like a hawk. Seemed fine. We had tickets for Silverstone this weekend and really wanted to take the TVR. After a quick call to Hawthorns servicing we decided to take a few bottles of water in case we overheated and go in the TVR anyway. Travelled up targa style and during the journey drove through what can only be described as a cloudburst of biblical proportions. Wipers on full, terrible visibility. Got mildly soaked, but was suprised how relatively dry we stayed, all things considered. The car didn't let us down either there or on the journey back, and water temperature was normal. However, every time I checked the expansion tank it was empty. I'm going to order Steve Heath's book today, but in the meantime, does anyone have any clues as to why I might be losing this coolant and how serious it is? Thanks in advance Jon 97R Chimaera 500

[trefor]

Could just be that after your previous overheating events the pressure cap has had enough. Doesn't cost much to replace. Also, after you stop from a run open the bonnet and see if the cap is 'fizzing'. Sometimes if the expansion chamber is too full (in the car's opinion) it spits the excess water out until it's got as much as it likes (obviously a pressure thing). You usually get a little puddle on the ground the first time out after filling up if this is the case. T/.

[JonRB]

Could be, Trefor. The thing that had me confused is that I'd driven it to work and back about 3 times since it came back from Hawthorns last Monday (ie. a week ago), but it wasn't until Friday that I noticed a puddle forming under the car just after I pulled up on my drive at home. Perhaps the cap had been on the verge of giving out and just chose to do it on Friday? I'm hoping that it is something simple like the cap as I'm a bit loathe to let the car go back for another extended visit to the dealers. Regards Jon

[ATG]

Hi JonRB ... hmm, another possibility ... there is a gasket lurking somewhere behind the stuff the serpentine belt drives and the main body of the engine. (That is how it was described to me ). I assume what this means is that it is the gasket that seals the connection between the water pump and the engine block. Apparently it is common for this to fail. Indeed, I was told that it should be considered to be a consumable. Mine appears to be going after 35k miles. Gasket costs next to nothing, but the labour is going to be painful, as it is inaccessible. The telltale sign is for a puddle of coolant to appear on the garage floor, and wet patches on the chassis directly below the gasket. I would have thought that if your problem was pressure related, e.g. expansion tank cap letting go too soon, then you would loose boiled coolant (i.e. a cloud of steam ... or *nothing* to see at all ), or a high pressure squirt of coolant being pushed out by the steam. If you're loosing coolant when the engine isn't running, then it must be falling out of the system under gravity, not being pushed out the top of a cap. If the dripping you describe is right up front, then maybe your radiator is leaking? If its just behind the serpentiny bits, then maybe its that gasket I described? I guess it would also be worth feeling around the hose clips for coolant, and checking to see if the drips are flowing along anything before hitting the ground.

[Foss]

Just as a thought....when you turn a hot engine off 'heat soak' occurs. The equillibrium of cooling versus heating effect is disturbed and the resultant heat build up may cause the pressure increase/coolant loss. It does sound like a good idea to fill the expansion tank, run the engine and watch where the fluid is evacuated. Keep an eye on the temp guage though!!