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Discussion Starter #21
Don’t suppose anyone has an idea where I can find a pic of the vacuum lines bu any chance.
 

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Vac lines are rather obvious. They originate at the intake manifold and there is usually a sticker in the engine bay to show the route. The workshop manuals have diagrams as well.
 

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Discussion Starter #23
Hi. Yes as you say vac lines are quite obvious but being a k jet I would have thought it would have that many if any at all.
although thinking about it knowing Bentleys way of taking something quite simple and making it as complicated as humanly possible it probably has lots 🤣
 

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At 180 ferenheit the coolant is within range with water wetter specs, so your block is running at expected temperatures. The block will shoot 145 to 160 f. Running normally. It sounds like your heater core is clogged or a heater valve if there is one is not opening. Sometimes the auto temp CPU can fail in the all closed position. If you are not getting any air through the system at all look for animal nests in the air system especially if the car has been stored for a long time. Yours in service. Scott.
 

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Discussion Starter #25
Hi Scott. I agree the engine is getting up to temp
heater matrix has been back flushed twice and I set up a loop on a pump to run som rad flush continuously through a bucket for 48hrs and can confirm the heater matrix is free flowing and clear
tested/ looked at the heater board to confirm both servos are moving to full positions on all settings and can confirm heater flap moves to full hot to full cold and other servo again moves full positions
water tap has been rebuilt and I can confirm it opens and closes and when heater dials are on full hot (over ride position) it stays fully open
I get full power from the fans and can confirm a STRONG blast of air through the vents

tomorrow (Saturday) I’m going to rig up an auxiliary heater matrix on a water meter to confirm flow as I’m now starting to wonder if the water pump is not flowing sufficiently
 

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If there any vacuum hoses you might find a schematic at www.heritage.bentletmotors.com where you can insert your chassis number and search various components.There should be a label showing the route of any vacuum lines (if there are any) somewhere under the bonnet, possibly near the front driver's side (RHD) behind the headlamp. My car is a Silver Shadow 11 with twin SU carbs so there are a few vacuum hoses but I'm not familiar with the vacuum set up on your Bentley Eight. One place where a vacuum leak can occur is at the gaskets between the inlet manifold and the head, usually a spray of WD40 at the joints while the engine is idling will reveal a leak when the engine stumbles slightly as the WD40 gets sucked in.
 

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Discussion Starter #27
usually a spray of WD40 at the joints while the engine is idling will reveal a leak when the engine stumbles slightly as the WD40 gets sucked in.
Yer that’s the plan for tomorrow. Im kind of hoping I find something but with a stable and normal idle speed I’m not optimistic but strange things have happened before
 

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If you check each spark plug you might narrow down the problem to a particular cylinder or two, if they're all grey/white then the air is getting in further upstream.
 

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Discussion Starter #29
Ok had a look today.
thought I’d do a simple process of eliminating which end of the car I was dealing with
so removed the air tube from the injection body and holding the car in gear briefly held the throttle at 2000rpm
with the air/ fuel meter connected the engine went very lean I then got a friend to slightly push the metering plate down the engine richened up and the car came alive.
so I knew that the engine was getting enough fuel / pressure so the back end of the car was ruled out as the source of the lean running . No fuel blockages/weak pumps etc
a spray around the inlet / metering unit showed nothing BUT when putting the car under load again and sprayed again the engine bulked !!
Complete removal of the injection body and manifold adapter reviled a piss poor previous repair of both the manifold to adapter gasket and the large rubber sealing ring of the injection body
both bodged with silicon!!
what amazes me is with the amount of work required to remove the injection body and manifold why would you bodge it with silicone!!!
This is a car with documented service history for the last 100,000+ miles going back 22+ years with the SAME and only specialist
and there a VERY VERY well know name Bentley specialist— I have the bill in the history for when the remedial work was done and the manifold removed -I won’t name them here but there work ain’t worth a monkeys
 

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At least that's another fault diagnosed, you're making progress. Eventually you'll have a reliable, fully functioning motor that you can enjoy, it will be worth the effort and persistence.
 

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Discussion Starter #32
Definitely- it’s just a shame you have to spend so much time fixing bodges especially when some of them must have taken longer then to do the job right in the first place
 

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Discussion Starter #33
Ok need to ask some of you much more experienced Bentley chaps a question
im having this lean mixture engine problem
now despite fixing all the air leaks inlet manifold/ injection body / o ring on bottom of metering unit- ok all changed and no more air leaks
so still the leanness of the engine persists
so I’m now been advised by a very experienced Bentley specialist that the ECU could be faulty I’m not doubting for a second that this is wrong BUT this is the bit bit I’m struggling with- when I worked at vw many years ago (I then went on to work at VW racing) we had the k jet on the golfs etc and the mixture / fueling was controlled by the metering unit position - I can understand the ECU to control spark by throttle position ,air flap position, fuel pressure etc BUT can’t see how on a k jet the ECU has ANY control over the air /fuel mix -there is not any way I can see how an ecu has any influence on injectors that fire via pressure only
please someone explain what I’m missing.
 

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Hello,

Bosch control units are near bulletproof, and the possibility of it not being good is near zero.
Does your car have an EHA (black plastic box) on the side of the fuel distributor?
Does your car have an oxygen sensor?
IETIS states that your car is equipped with two fuel pumps, correct?
 

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Discussion Starter #35
Hi yes. My car has 2 pumps -I’ve checked the fuel pressure’s
yes I have the EHA which I assume tells the ecu the flap position
no no lambda
 

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Discussion Starter #37
Hi wraithman- sorry my last post was a bit ambiguous in my wording i know what the EHA is /does - what I meant was ‘I assume it tells the ecu where it is as in supply more fuel for accelerating/engine load etc ‘ but it’s not contributing to my lean engine problem as my engine is lean from Idle getting leaner to WOT also I don’t get any other EHA failed symptoms
but appreciate the clarification 👍
also does anyone have any ideas on how to tidy the seats up on the metering unit. -I have one that won’t seal -and was considering a light stone on a dremal
 

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It would be prudent to have your metering unit, cleaned and flow tested. It has been in service for a long time and a critical component within the fuel system.
 

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Discussion Starter #39
Yer I think so. I’ll get a price on an overhaul and compare price to a flying spares recon at £330
 

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Are you in the US? If so, there is no need to buy from FS. There are many companies that recondition fuel injection components in the US.
 
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