Help ! At the end of my journey to work this morning, when pulling off the motorway (uneventful 30 mile journey, cruising at 70ish. I noticed the temp gauge was slightly above normal (indicating just over 90 rather than just below). Then a few wisps of steam out the bonnet when I stopped at traffic lights, temp gauge rising very slightly, so I whacked the heater and fan on full, which only put out intermittent warm/cool air rather than the expected blast of scorching air but the temp gauge did fall back to normal. I nursed it a couple of miles to my work car park, temp gauge didn’t climb any more. Opened the bonnet, coolant has been leaking out the expansion bottle cap and steaming where it hits hot engine parts.
I slowly undid the expansion cap, there was pressure in the system and some more coolant bubbled up and out, then stopped. It was hot but not enough to burn/scald me. Also the rocker cover was hot to the touch but no more than I’d expect. So I cautiously started the engine , expansion cap off (temp gauge still showing normal), the water level in the expansion tank dropped, then after a few seconds rose up and bubbled over, so I switched off the engine again. It had started normally, idle seemed to be smooth and normal and there’s no sign of water or steam out the exhaust.
What are my options here – Coolant leak somewhere, level too low, causing steam generation in the head and excessive pressure ? Or head gasket gone ?
What are my best options to get home (30 miles) and deeper investigation tonight if I can get back. Should I top up the water, and take it for a short test derive at lunchtime, or go get some radweld ?
Also I happen to have a cylinder compression tester in my tool box in the car as I’ve been meaning to check it as a matter of interest, I’ve only had the car 6 weeks. How would I detect a cylinder to water leak with a compression tester ?
Car details - R reg cento sporting, bog standard, running great, 80Kmiles. Had the head gasket done by the PO (£750 garage bill) about 10000 miles ago, along with a new rad and thermostat.
I slowly undid the expansion cap, there was pressure in the system and some more coolant bubbled up and out, then stopped. It was hot but not enough to burn/scald me. Also the rocker cover was hot to the touch but no more than I’d expect. So I cautiously started the engine , expansion cap off (temp gauge still showing normal), the water level in the expansion tank dropped, then after a few seconds rose up and bubbled over, so I switched off the engine again. It had started normally, idle seemed to be smooth and normal and there’s no sign of water or steam out the exhaust.
What are my options here – Coolant leak somewhere, level too low, causing steam generation in the head and excessive pressure ? Or head gasket gone ?
What are my best options to get home (30 miles) and deeper investigation tonight if I can get back. Should I top up the water, and take it for a short test derive at lunchtime, or go get some radweld ?
Also I happen to have a cylinder compression tester in my tool box in the car as I’ve been meaning to check it as a matter of interest, I’ve only had the car 6 weeks. How would I detect a cylinder to water leak with a compression tester ?
Car details - R reg cento sporting, bog standard, running great, 80Kmiles. Had the head gasket done by the PO (£750 garage bill) about 10000 miles ago, along with a new rad and thermostat.