I dunno, Kirbert makes a valid point about the rising coolant level at the crossover filler when the engine is running… I’m not sure what else could cause that other than the HG…
With the cap on though it has never vented steam or coolant…
The lack of power is since I bought the car, but the high temperatures when pushing it are only something I’ve noticed since the radiator change… but could that actually be hot gases entering the coolant when I’m pushing it, I wonder?.. so many unknowns!
Just throwing this out there, belt for water pump? Maybe it’s slipping at high rpm?
Interesting suggestion but I don’t think it’s related to RPM - it seems to be when going up hills or going particularly quickly that the temperature darts up and then darts back down again…
Annoyingly in every case by the time I’ve pulled over and opened the bonnet it’s back down to the N…
Well, I mean combination of load and rpm. As you put load on car, rpm goes up too, as does engine temps. If belt isn’t tight, then the pump isn’t moving the coolant fast enough.
Is the belt tight? What does it look like?
What about a stall rpm value to compare against. What happens to temperature?
A head gasket can fail without too much notice. Especially on a v12 I guess. Simple things first - bleed - stall test - timing - plugs out, look at them, leak down test.
Good luck in any case.
David
I have never heard any pinging in my girl since I went from 91 to 95 octane. But I tried using 98 and I found that my economy improved dramatically. I concluded from this (probably get shot down) that there must have been some inaudible pre-ignition taking place with the 95 thus limiting the power.
There is a lot of aluminium and water in that engine, it is not easy for it to significantly shift up or down in temperature over 10 to 20 seconds.
I would take the temp sensor out and put it in a container of water where you can heat or cool it over the “N” range which is about 80deg C. Obviously with the ignition key on but engine off.
See what the gauge does.
When driving above idle speed the alternator puts out a bit more volatge, not sure if that will afect the gauge reading.
The V12 cooling system is most challenged at idle and should perform better at speed. However long uphill stretches will impose more heat load on the system but even so the coolant takes a fair number of minutes to react.
The symptoms appear more to do with measuring temperature than actual coolant temperature.
The reported lack of power could be a totally different problem seeing it has been there since the car was bought. The gauge problem only happened after recent work on the car.
Could your water pump be sucking the bottom hose flat at high rpm and stopping water flowing through the radiator? Check if it is soft/spongy. There is a fix in The Book to put a stainless coil in the hose to stop this happening.
Interesting notion. D’ya suppose that the hose sucking flat would cause the fluid level to rise in the filler neck?
Still hard to imagine the hose sucking flat at idle, which is apparently when this fluid rise occurs.
I think there are multiple issues here. So going diagnosing all the possibilities, and fixing each as the problems are found is the only way forward.
I take it the heater matrix has been in the system when filling up the coolant? Not sure if this point was raised in any of the posts?
I would bet on the centrifugal advance being seized and the vacuum advance can leaking for the symptoms described. I doubt that the shop knew to check timing at 3000 as Jaguar specifies.
Timing lights are not overly expensive, get one with an advance dial as it will make it easier to read 18 degrees; when checking the timing rev past 3000 and drop back to that speed.
You can then compare that to the idle timing to see if the advance mechanism is sticking.
Very Doubtful you have any head gasket issues based on compression and no gases in coolant.
Lower hose looks alright so I don’t think that’s the issue.
Heater matrix was indeed in theory in the system, and the heater seems to work.
Last time I checked (about 8 months ago ish) the centrifugal advance seemed okay (the rotor moved easily back against a spring force) and the vacuum advance was holding vacuum and moving the rotor.
I am suspicious of the timing though so I think I will rule that out next, though I guess the performance issue could also be fuelling? But I’m not seeing any smoke or anything like that or hearing anything unusual.
Firstly though I’ll try bleeding it properly!
Be sure to disconnect vacuum advance (which is a pain); if checked when connected will throw the setting way off.
Another backyard way to set timing (will get you close) is using vacuum gauge at idle; adjust for maximum vacuum at idle (with vacuum advance connected, doesn’t matter); then back off 1” vacuum. Dependent on everything being operational.
So, went out to it today and with the filler cap off it is now ejecting water immediately when it starts. Not a good sign. But my exhaust gas detector liquid still is not turning yellow, which is weird.
Weirdly though, if I open the bleed screw on the rad, this does not eject water, even after running it a short while with the other caps on…
Check that distributor before going too far in any other direction that will cost $$ and time. Since it is an '88, you likely have the Lucas ignition and distributor. These do not age well and a good cleaning and lubrication is essential. Poor distributor function (advance operation, that is) will easily contribute to overheating.
-M
you sure thermostats are good and installed correctly?
Update: Turns out, if I run it with th efiller cap off and the radiator bleed screw out, it spews water quickly.
If I run it with the bleed screw in, though, it only very gently rises up.
Running with the cap fitted and the bleed screw out, I get nothing for a few minutes and then eventually a very gentle flow of water…
As long as you brought up thermostats…
Are they the correct thermostats?
If they’re too short and don’t block-off the bypass ports, would that account for the symptoms described?
I’ve been mulling this but am unsure.
Cheers
DD