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Discussion Starter #1
Any thoughts very welcome
1 ~ I have a really poor heater. -20 mins of driving and it can only just about defrost a window
things tried ……
new BENTLEY thermostat-no change engine gets up to temp but done that on original
rebuilt / confirm working WATER TAP no change
check circuits/ servo operation to flaps no change
back flush heater matrix perfect clear no change
on days like today -1c car stays parked up as no fun driving in coat and jumper

2 ~ car 1992 k jet Eight is gutless piss poor acceleration on a flat motorway at 70 mph it takes 12 seconds to get to 80mph when foot held to the floor. (Not kick down just full throttle)
on a wet roundabout car does not have enough power to spin a wheel in anger ! Even using kick down
things tried.
replace fuel filter with genuine Bentley
check getting full throttle at throttle body.
will do more checks tomorrow
fuel pressure / full throttle switch etc

handbrake does not self release when put in gear.
not looked at yet
 

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Discussion Starter #2
Ok. Had a look at the Eight today and although I don’t have the correct adapter to test the fuel pressure on the K jet I do have an AFR gauge to measure air /fuel ratio . At idle it’s perfect at 14.7afr. However when driving it leans off -noticeably like as soon as you touch the pedal
I have a Bosch motorsport fuel pump hanging around so might try that as the original one has done 145,000 miles so might not be giving the pressures required or maybe a sticking flap in metering unit (but think doubtful )
could also be a leaking accumulator venting pressure back to the tank but car starts on the button hot or cold so again doubt
open to ideas.
 

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There is a possibility of a clogged catalytic converter.
 

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Pro heating:
If all those elements were checked and are good for sure, try temperature sensors. However I believe that even with bad sensors in defrost mode it should heat. Is blower working?
 

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Discussion Starter #5
There is a possibility of a clogged catalytic converter.
I dont have a cat on my car.

blowers are fine. Both working correctly
even on defrost it’s no different
it’s like the coolant is not hot enough
funny even after 30 miles of driving you can hold any hose ( although not the rad as it’s alloy )
 

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I dont have a cat on my car.

blowers are fine. Both working correctly
even on defrost it’s no different
it’s like the coolant is not hot enough
funny even after 30 miles of driving you can hold any hose ( although not the rad as it’s alloy )
So, vents just blow cold air, the gauge show that engine is all the time cold and external measurements confirms that?
 

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Discussion Starter #7
Hi. No vents blow cool air with a touch of warm
engine gets up to running temp (around a third up the gauge )
laser temp gauge shows stat housing around 83-85c but all engine hoses are warm /moderate but even top hose never gets hot enough where you can’t hold it It’s hot but you can hold it -it’s never hot enough where you would hold it let it go and go f00k me that’s hot.
 

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engine gets up to running temp (around a third up the gauge )
laser temp gauge shows stat housing around 83-85c but all engine hoses are warm /moderate but even top hose never
Did you try to measure temperature of hoses before and behind water tap with laser temp gauge? Just to be sure that it is open? Of course while engine is hot. Ev. hose returning from heater too.
 

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Discussion Starter #13
Hi yes. It can be rotated quite easy.
but I’ve ordered a new one just as point of elimination
 

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I suspect that your new thermostat is a dud or the wrong type or maybe fitted upside down (if that's possible). Either that or you have a serious air lock in the cooling system and your heater matrix isn't getting any coolant as it's the highest point in the system. If the viscous fan was slack it would cause overheating not underheating..
 

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Discussion Starter #16
The thing with the stat is this is the third one. First I thought the original was wonky as I had only just bought the car so I removed it and fitted a Renault one that pushes in the top hose - no difference but was advised by chaps with lots more experience on these cars that it was not a good idea so I went and bought an original again no different I have filled it from the rad bleed point- I have vacuumed it down and filled it -I even ran it with a calgon tablet inside for 400 miles ( works better then “water wetter “ ) in case there was a slight blockage
but now I’ve confirmed it’s running lean I need to sort that first
 

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The usual cause of lean running is a vacuum leak at the inlet manifold, if you detach and replace one vacuum hose at a time until you notice no change in running you may narrow down the vacuum leak if there is one. Lean running also tends to cause an engine to run a little hotter rather than colder so sorting the fuel/air ratio won't fix your cooling issue. Looks like you have a few things to sort so focus on one problem at a time. You'll get it sorted eventually and the persistence will have been worth the effort.
 

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Discussion Starter #18
Hi agree that an engine running lean runs hotter what I meant was I can’t use the car until the fueling side is fixed
I have a smoke machine so will give that a try over the weekend on the vac lines
 

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Regarding the coolant I'm not sure which type of header tank is fitted to your car, if it's the metal tank on top of the radiator then coolant is filled slowly by simply pouring it into the header tank but if you have the later plastic header tank there's a special process for filling the coolant that involves removing the hose between the header tank and the rad and raising the hose to avoid spillage, then filling the rad and reconnecting the hose and topping up the header tank. It's best done with the front of the car raised and the heater set to defrost to expel any air that could be trapped in the heater or thermostat housing.
 

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Discussion Starter #20
Plastic header tank. Hi yer that’s how I filled it. As I said I’ve tried filling it as per the manual and using my vacuum filler.
I don’t think at this point it’s an air lock
I’ve even took the engine fan off and let it sit there till the electric ones kicked in. None of the hoses get hot enough not to touch. The only thing that gets scalding is the rad but that’s cos it’s full alloy
 
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