1-7 td bosch pump?

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goldfinche
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1-7 td bosch pump?

Post by goldfinche »

Hello everyone I have a question or two about a Bosch pump.On the engine side there is the exspected wax stat operated lever for the revs at tickover hot or cold. It does not work and as such causes no problem at all.
On the radiator side of the pump there is a long lever that is ( or should I say should be. ) operated by a large wax stat fed by two water hoses. The question is what does it do? Because when the engine is cold ie. stood overnight the lever is about 3/16" off it's stop. When the engine is at running temperature it's about 1/16" off the stop which makes me think that the wax stat is U/S. When the lever is moved by hand, it's quite stiff, it does not seem to do anything, there is no change in engine note or diesel knock etc. hot or cold. When hot should it be against the stop and can it cause any problems if it is not?
Any thoughts etc. would be welcome.
Thank you.
Geoff.
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AndersDK
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Post by AndersDK »

Geoff wrote :
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Hello everyone I have a question or two about a Bosch pump.On the engine side there is the exspected wax stat operated lever for the revs at tickover hot or cold. It does not work and as such causes no problem at all.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
If it does not work - then the tickover is rather high. Should be some 1000-1100 rpm as the coldstart never releases then.
If the tickover is normal (850) despite the defunc waxstat - then the hot idle has been adjusted down to compensate. But the cold start timing offset is constantly held - unless this has manually been offset too.
This could very well be the reason why you dont see (or hear) any change from the "other" waxstat jobbing.
citronut
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Post by citronut »

that sounds like its working fine,when tere is larger gap it should be holding revs up a bit,the wax stat for this is usuly screwed into thermostat housing with a cable going to the lever,i dont know of another stat for fuel pump,sometimes they have a canistersticking out of the front of pump with two wirers going to pair of contacts,this unit is a servo which adjust pump timming when cold regards malcolm
goldfinche
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Post by goldfinche »

Thank you Anders err umm Sorry I remain somewhat confused.To explain a little better I hope, the little lever that controls the tickover revs has had the cable slackened so that the revs are not altered be it hot or cold, there is no problem starting and running from cold. Tickover revs are 900 rpm.
It was the fact that the long lever on the other side of the pump (radiator side.) was held off it's stop by the cable from the wax stat even when the engine was hot that was a consern, also that it did not seem to do anything when moved, with engine either hot or cold. So what does the long lever do? The 2-1 diesel in the XM has the same layout with 2 wax stats and 2 levers.
Sorry I am trying to tie up the reason for 2 levers and work out why its necessary to have 2. It's not making a lot of sense at the moment.
Sorry to be thick.
Cheers
Geoff.
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fastandfurryous
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Post by fastandfurryous »

The waxstat in the thermostat housing with a bowden cable operates the idle speed lever, and nothing else. It raises the idle speed on a cold engine. I've had something like 30ish XUD engines and not one has ever worked properly, and it's not a problem. The unit fails in the "hot" idle position, which is the normal (or slow) idle speed.
The waxstat on the front of the injection pump with it's little flow and return pipes operates the injection timing, and nothing else. It (slightly)advances the injection timing on a cold engine to reduce startup smoke (but also does create a bit more diesel clatter). It also failes in the "hot" operating state, and when failed the engine will still start and run just fine.
Personally, I woudn't worry about either of them. Some people swear by having the faster idle when the engine is cold, but personally I would rather have the engine idle slowly at the instant of start-up so that it has time to build oil pressure before running at anything over 700rpm. With the idle waxstat working, the cold idle can often be 1000-1200 rpm, which I don't like to do on a cold engine. Maybe in sweeden/iceland it's essential, but in the UK both waxstats are fairly irrelevant. I've achieved starts in -20 winters in scotland with failed wax-stats with no problems. Working Glow-plugs and good injectors are far far more important.
goldfinche
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Post by goldfinche »

Thank you eversomuch got it now. On all the BX's we have come across I cant remember a fully functioning Wax stat for the cold starting revs, so they are disabled because of the high revs cold start thing it can not be any good for the engine or turbo.It could be that I am simply old fashioned and modern oils etc. do a good job.
Cheers for that you learn something every day.
Best wishes.
Geoff.
ScottFromNZ
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Post by ScottFromNZ »

My BX TZD turbo (with Bosch pump) had a "clattery" idle when warm some time ago. I found that while the waxstat that raises the idle speed when cold (via a cable from the thermostat housing) was working fine, the cold pump timing advance device at the front of the pump (the one with the coolant hoses going to it) was not releasing fully when warm. So the timing was advanced a bit all the time which resulted in the clattery idle. I simply adjusted the cable on it so that it released to the fully retarded (hot) postion.
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