I have a 1976 4.2 XJC (Canadian spec). My radiator fan having recently flung itself into the radiator (see thread Screech noise - fan or belt?), I have had the radiator replaced with a “high performance” aluminium model. At the same time the mechanic (not a Jaguar specialist, I did not have much choice, but a specialist in restoring older vehicles) took the opportunity to replace the leaky cam cover gaskets and tinker with the Stromberg carbs (previously running a bit lean, resulting in a flat spot until really warmed up).
Saturday morning I drove 40 miles of hilly country roads without incident, and no more flat spot, although when entering town and an underground car park at the end, the indicated engine temperature approached the “a” or “normal”. Ambient temperature high 20s centigrade. This was a faster pick-up in temperature than I had experienced before. I have air con but was not using it.
On the way home, I took the motorway and during the long upward slopes at approx 70mph noticed brown / black smoke behind and at the same time a drop in indicated oil pressure towards zero. Previously it would be around 20psi or so (it’s never been high). The smoke would disappear on the downhill stretches but pressure stayed low. Smoke came back on the uphill slopes. Engine temp displayed a bit above the middle of the gauge, but well within “normal”.
Stopped the car, temp rose to the “l” once stationary, observed oil leaking around the rear of the engine (not the cam covers) and burning off, and some residual brown smoke (not blue) from the right hand exhaust.
Didn’t want to risk it, so had the car towed. No other issues, no flat spot, that’s what I know so far. I don’t know if the mechanic filled the coolant using the correct procedure (he used a mix of coolant and water though, previously I used pure coolant).
I am surprised that the temperature rises more readily with the new radiator. I am using the same 88c thermostat. My mechanic claims that that is a feature of aluminium radiators versus steel but it is not overheating. He also favoured installing electric fans but following much debate I asked him to stick with the original set-up (including new thermal clutch), reasoning that it should work perfectly well if properly installed and I did not fancy upgrading the alternator to feed the fans.
So I am seeing views please on the issue here. Is it running too hot? Too rich? Why the sudden oil leak? Do I stick with the mechanic who by now knows the car somewhat, or is it better to start afresh with someone else?!
XJC 4.2 Series II (1976, Canadian spec)