Lucas boost compensator removal and repair?

[ghaddon1701]

Hi,
I removed the pipe that goes from the intercooler to the injection pump on my TZD. When the car is running diesel drips out from the boost compensator valve on the pump. I assume that this is not supposed to happen? I was wondering that the diaphragm inside the compensator might be split or on its way out? I assume this could also be why I seem to be down on power?
Does anybody know if you can replace the diaphragm? Also how do you get the boost compensator off the side of the pump? Pump has to come out? Then what? Thanks.

Regards Graham

[mds141]

Does the valve split? I remember Graeme McNulty doing a diaphragm repair using bicycle inner tube. Split the valve, use the inner tube as a new diaphragm, rebuild the valve and then trim off the excess rubber. Not sure if this will work with this particular valve.

[ghaddon1701]

I am not sure if it splits or not. I can't even figure out how it is attached to the pump to remove it. It is not in two halves(help together by screws) like the bosch version. Access isn't brillaint on the BX without taking the radiator out either. I am not even able to find replacement boost compensators for sale anyhwhere. Let alone any information on removing it from the injection pump.

[themildbunch]

Hi,
I removed the pipe that goes from the intercooler to the injection pump on my TZD. When the car is running diesel drips out from the boost compensator valve on the pump. I assume that this is not supposed to happen? I was wondering that the diaphragm inside the compensator might be split or on its way out? I assume this could also be why I seem to be down on power?
Does anybody know if you can replace the diaphragm? Also how do you get the boost compensator off the side of the pump? Pump has to come out? Then what? Thanks.

Regards Graham

be v. careful of this - see my recent thread: massive TD runaway....

With hindsight mine had probably been leaking slightly for quite a while as I'd been getting odd raised revs occassionally.. It went big style though, lots of diesel got in the intercooler causing a scary if fairly brief runaway...

I have a good spare off another pump I haven't got around to doing yet but the whole boost compensator is available which includes the diaphragm for about £93 + VAT at my local diesel specialist... Part number is: 9100-633

IIRC they won't sell just the diaphragm on its own anymore..

[ghaddon1701]

Thank you for that. Do you know how to remove the boost compensator assembly from the pump? Does the pump need to be stripped? Or can you unscrew the allen bolt in the centre of it and it comes out? Thanks.

Regards Graham

[hilarystone]

I had the boost compensator done on my CX with a Lucas pump in April - its a straightforward job for a diesel specialist and cost just an hours labour. You need the whole kit as I understand the design has been slightly changed. It certainly made a huge difference on the CX which was extremely lethargic before and is now totally transformed...

[ghaddon1701]

From what scraps of information I have managed to find out searching the internet it seems that the failure is quite common certainly on the older Lucas pumps. If a its a simple job for a garage to do I may give them the job. should be plenty of diesel specialists in Birmingham. Thanks.

Regards Graham

[docchevron]

it's possible to replace it in situ, but not easy due to it being a bit buried. For the cost of an hours labour, if you aren't confident, then I'd say it's money well spent.
And yes, the replacement units are slightly different and a bit more manly to stop them failing.

[KevR]

be v. careful of this - see my recent thread: massive TD runaway....

With hindsight mine had probably been leaking slightly for quite a while as I'd been getting odd raised revs occassionally.. It went big style though, lots of diesel got in the intercooler causing a scary if fairly brief runaway...

Sounds from this like mine my be on the way out too - turbo performance has never been very impressive low down and lately it's taken to revving up a bit on its own every now and then. Hope it'll last another week or two though as I'm off on another epic trip back to UK next week and don't really want to be mucking about with that before I go...

[KevR]

A further twist...
Thought I'd just go and take off the pipe from intercooler to BC valve on the grounds that if it was half full of diesel that would confirm the diagnosis as a failed diaphragm. Pipe was still fitted with original Cit hose clips and has certainly not been removed since I've had the car (5+ years) and before that it was stood for several years, and before that the previous owner didn't do much maintenance I think, so that pipe's been undisturbed for a decade at least.
Pipe was indeed completely full! But not with diesel... In fact it's full of old black engine oil. I can only assume this has collected in the I/C having been through the airbox from the crankcase breather, then run down into the pipe. Removed pipe and took a spin up the road, Very little difference in performance to before although perhaps less inclined to rev high. Cleaned pipe and refitted - now goes like a turbo should!
Have sourced a good spare pump and BC valve anyway so will take the valve with me this week just in case, but pretty confident that even if the original gives up big time then simply blocking off the diesel feed pipe should allow me to get there and back again not much slower than I would have with the pipe filled with oil!

[docchevron]

yep. Unless you have catastrophic run away then you can block the pipe off and all should be ok, just a slightly uninspiring drive..

Might be worth checking the turbo itself though, they can pass a lot of oil if the seals fail..

[KevR]

I've got a spare turbo from a (relatively - abot 100k) low milage engine so one day I'll give that a looking at. There's always a fair bit of oil in the airbox/filter so you could well be right.

As for the uninspiring drive, I can put up with that - this one's never been very inspiring anyway - so long as it gets me there and back!

[docchevron]

oil in the airbox *can* be caused by the breather valve failing.. so worth checking that too, since they never EVER get checked o changed...

[KevR]

Now you mention it, last time I changed the air filter I also changed the breather valve for one from my low mileage scrapper. Since then the area round the breather valve has stayed dry (it was always oily before) so presumably that's working as it should, Will check the filter if I get a chance this afternoon.