Unusual for a V12 HE perhaps but mine now take ages to reach normal running temperature I have changed thermostats of course, it used to heat up quickly due to clever design?
It happened following a general service.
Can anyone help please.
David
Do you know if engine is getting up to temp. but the gauge is not reflecting this. Sender not working correctly, disturbed wire at sender?
It does eventually reach normal temperature by the gauge reading and by general other indications eg the fans come on and go off when the gauge shows ‘N’ but they don’t on come on before that point. Have checked general sender security. Engine behaves as though there were on thermostats in it. I wonder if some hoses could possibly have been incorrectly fitted in some way. The radiator is supposed to be out of the circuit until the coolant gets hot enough. Seems as if it is in all the time. Only since the service which included hoses.
Check the thermostats - sounds like they are not closed fully
The garage said that had changed them but I though they had left them out so I got two new ones but when I did the work they were if fact thermostats in there - still fitted my new ones, but it made no difference.
I just popped a re-cored radiator in my '87 and the temp gauge and after about ten minutes of idling the temp gauge is still below the ‘N’ mark.
Looks like I need to check and see if the previous owner hads’t removed the thermostats…
Dan
Gauge readings at normal temp are all over the place, from car to car. Why assume it should reach the N, if you don’t know what temp N actually equals?
Mine runs at halfway between C and N.
For the earlier barrel gauges, cars with 180F thermostats typically run halfway between C and N. Cars with 190F thermostats run around the bottom of the N itself.
Many thanks for all comments. I believe the point has been missed. Its not the eventual temperature that I have a problem with, it is the time it take for the engine to attain that temperature. I don’t know what the value ‘N’ actual is but mine has run just slightly below ‘N’ since I bought it and still does. The issue I have is that whereas the engine used to heat up quickly, which is desirable, it now takes about 20 - 25 mins to reach the final temperature and we are in summer! On short journeys the engine never properly heats up, which is bad. I think somehow, no idea how at this time, the coolant is finding its way through the radiator before the thermostats have opened. The thermostats are being by-passed. With the complexity of pipe-work on this engine and the difficulty of seeing it all clearly due to sheer amount of hoses and routes, I can imagine that this could happen.
Dave, How long have you owned the car ? Your profile shows you joined J/L around 6 months ago…so maybe a bit before that you got your car ? I ask because maybe you are still learning the ins and outs of the V12 engine. I think based on your concerns that I would ask the shop exactly which hoses they replaced. And then knowing that, I would find a schematic of the cooling system and how the coolant moves thru the system. It’s not at all complex. The Haynes Manuel # 49015 page 334, while not the best reference, is a start. And while you indicate the operating temp is not a concern, you might opt to buy, as some owners do, an infrared temp sun, to check actual engine temps at various locations. Good luck, SD Faircloth www,jaguarfuelinjectorservice.com
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Agreed, 20 minutes is too long for warming up. It should not be possible for the coolant to reach the radiator when the thermostats are closed; it should all be bypassing straight back to the pump inlet. There are only three possible ways around this, I think. First, there are the jiggle pins on the thermostats themselves, but they shouldn’t provide a significant leak. The second is the heater circuit; if open and flowing, this will cool the engine even with the thermostats closed – but this has always been the case, not sure what could have changed recently on your car. Third, the automatic air bleed system could be pulling some coolant from the top of the radiator to pump inlet, but those lines are so small and the flow so tiny it’s difficult to imagine them keeping your engine cool.
There is the possibility that your engine is warming up as usual but the gauge isn’t showing it. The gauge sender is screwed into the A bank thermostat housing. If it has an air bubble around it, it’ll take forever to respond to changes in coolant temperature. Or, if for some reason it’s sensing the temperature of the metal of the housing rather than the temperature of the coolant, that’d make it respond slowly as well. Do you have indications that the engine truly is running cold for that long?
Thanks SD, I bought the car new a long time ago and have become very familiar with it. I do have workshop manuals ane the Haynes. I do as much as I can so that it is done properly! Of course many jobs are out of my ability due to lack of a proper work shop and sheer man power. The eventual operating temp is fine but as I say, the engine takes too long to get there. I spoke to the garage but they are not really interested as long as it runs okay and I pay the bill! Thanks for your good wishes. D
Thanks K, I have looked more carefully and I cant see anything wrong with the hose positions - they all go where they should do. The other possible coolant path could be via the hose from the top of the manifold just before the thermostat on one side which goes to the expansion tank - I don’t know what it is supposed to do - was not on the pre HE engine. It is big enough to let quite a lot of coolant pass which would then find its way to the bottom of the radiator via the tee junction on the expansion tank. However mine does not have that tee and the tank has only two connection points on it and may have been incorrectly fitted at some point. My matrix output goes directly to the bottom hose fixing in one metal pipe, the same as another member recently wrote. The early HE models were all one off’s to some extent. The engine had always warmed up swiftly and the temperature gauge always rested just below ‘N’. The other indications are the fans don’t come on for ages, the idle speed remains higher than it does at full running temperature for longer and even the caps don’t feel particularly hot, nor the heater. If I let it sit there just idling then it warms more quickly. Obviously the ECU takes care of the running mixture all the time but the temperature gauge is a separate fairly simple circuit and checks out okay. David
Is your car US spec or EU? Can it be that your ignition retard timer stopped working and you don’t get retarded timing after startup for faster warmup? Just an idea…
Interesting idea John and may be the answer. The garage who worked on the engine said they has ‘adjusted’ the timing. I don’t know which way but I could ask them. Its UK made for our market so I don’t know if it has that particular feature. That whole part of the engine is extremely complex as you probably know. A lot of component parts can fail without significant effect on the running. The car had been a bit neglected for a while and they did the inlet manifold gaskets and all the usual things - plugs distributer & leads aux air valve and so on. Runs very well now, idle is perfect and acceleration is rapid, so I cant expect them virtually to re-build the engine without a huge bill. Not many garages in Jersey who are able to work on these engines, plenty in England. David
Meant to say to you Dave that I joined because the forum is very carefully and wisely written and there are few engineers here who can diagnose the complexities of this engine. I found I had to find the answer myself in a lot of cases and simply ask for the work to be done. eg the plugs are a real pig and I just got fed up doing that stuff ! The climate control, particularly the air con, seemed to be beyond any one here so I got all the stuff and do it my self which is actually very easy - works very well. There have been numerus other things over the years, the cold start issue which is so widely discussed and about which no one seems to have definitive answer is only a electrical failure of sorts but three garages here could not fix it. David
All depends upon where the gauge eventually settles before you start looking around! David
The garage changed the timing. And now it takes a while to warm up. Any other changes? What’s the current timing @3000rpm and what vacuum advance components does your engine have?
Hi J, they don’t freely tell you exactly what they do. The engine was running rough, bad idle, bad fuel consumption and sluggish acceleration. The problem was diagnosed (correctly) as inlet gaskets letting air in. They replaced quite a few vacuum hoses and other usual stuff (as written in my last posts). You may be aware that there are many components some of which are interdependent of one another in that area. I imagine that the components in mine are as per the UK version but its hard to see them all. I don’t know what the timing is at 3000rpm and I don’t have the means to measure it. I can only imagine that the timing was adjusted for a purposeful reason. I could talk to the chief engineer about that particular matter but they tend to have the attitude of ‘well is was rough and it is now good so what is the problem’ The attitude regarding these old vehicles is not particularly enthusiastic over here. Working on this engine is very time consuming and hence expensive so I do as much as I can myself. David
Hello K - Reading your letter again I forgot to mention, there are no ‘venting‘ actual parts on the top of the radiator. The Haynes diagram suggests that there is something in circuit with those thin metal lines. The coolant actually goes by small hose from filler head to the rad (banjo) then sits on the top of the rad to the other end then tees to the expansion tank and manifold top just before the thermostat. There are no venting components as such, just tubing, but perhaps this whole arrangement is the venting?