Pump output union leak on 19TGD

[DLM]

I'm working on a friend's '89 19TGD which developed a bad LHM Leak recently. The drippage - pretty vigorous - was coming down in the general area of the gearbox bellhousing, and was traced to the union at the output of the hydraulic pump.

LHM could be seen coming from the inner part of the union and the pipe. The union was a little loose so I tightened it, but to no great effect.

Today I unscrewed the union, replaced the seal with a new one after careful matching and reassembled. The result - more of the same. I'm assured by the owner that the leakage before and after is from the same place. I'll try another from my new stock tomorrow, as same-diameter seals from different sources seem to vary.

Has anyone had a problem of this sort before? I've done plenty of hydraulic work in the past and never experienced this before. One thought which occurs is that the union must encounter twisting forceswhen the HP belt is tightened, and some friction may have occurred.

Anyone expereinced anything similar?

[Geoffrey Gould]

Hi DLM I have come across this before and found that the seal for the pipe seems to come in two definate lengths and on mine it was a long seal, I didnt have one so as a temperary I used 2 short ones. Maybe it would be worth checking that you have the correct length. I could of course be teaching you to suck eggs ,in which case OOPS sorry.
These pipes are known to fracture because the clip holding them to the block is loose or missing.
A final one is that the flow of LHM up against the pipe where it bends after it's exites the pump has been known to wear through the pipe.( Ok not the LHM exactly but the particles of metal etc. in it.)
Hopes that of some help.
Cheers.
Geoff.

[DLM]

Many thanks for your suggestions and comments, Geoff.

[/" Hi DLM I have come across this before and found that the seal for the pipe seems to come in two definate lengths and on mine it was a long seal, I didnt have one so as a temperary I used 2 short ones. Maybe it would be worth checking that you have the correct length."]

The original seal was a short one: I had two or more same-diameter seals in my box which were longer. First attempt was with a "short" seal o f the same length as the one I took out but I'm about to try a longer one.

"These pipes are known to fracture because the clip holding them to the block is loose or missing."

The block clip was present and correctly adjusted - so I had to unbolt & replace it when changing the seal .

"A final one is that the flow of LHM up against the pipe where it bends after it's exites the pump has been known to wear through the pipe.( Ok not the LHM exactly but the particles of metal etc. in it.) "

I'm assured that the LHM was coming from the union, not the pipe bend - but it's a good point. Sometimes even the heaviest-duty pipes wear in unexpected places and ways. I recall finding Ed a "loop" pipe from a scrap-car Pressure Regulator to replace his. That had been worn through by sustained vibration against the wire-mesh cover of an air intake hose - about the last and least abrasive thing you might think of.

I'll report on progress - and no offence whatsoever taken on the egg-sucking front Geoff.

[DLM]

Got it! the Pipe itself has split around its circumference just outboard of the flare - maybe a result of stress when adjusting/tightening the pump belt? One to watch out for.

Should have a pipe somewhere in the vaults from a 19RD dismantled many moons ago, but I'd be grateful to know if anyone else has one. It's the pipe from HP pump to flow distributor on a diesel.

[AndersDK]

Hi David -

For reference :
95.596.564 HYDRAULIC TUBE DIAM 6,35-565
- DIESEL FUEL AND 1,769L
- DIESEL FUEL AND 1,905L
Some £23 exvat at your friendly dealer

[DLM]

Many thanks, Anders, but I found my spare remarkably quickly - in fact in the first location I tried! This is a minor miracle by my usual standards. I'll keep the number or reference, though.

The spare pipe was fitted today and all looks well. The £50 19RD I bought to strip some 5 years ago has now provided hydraulic salvation for at least 3 BXs since - and I must have used many other parts that I can't recall at the moment. There are still some parts remaining in the spares box(es) too.

The broken pipe was only clipped to the engine in one location - nearest the pump. However the donor pipe had two clips (as does the same pipe on my 17 TZD turbodiesel). As the only possible front clip mounting point for this '89 TGD was a starter motor retaining bolt, I suspect the clip was 'deleted' during a starter motor change. Whether this influenced the pipe break is another matter. I attached the front-end clip to this retaining bolt as I don't want to prove or disprove any theories...

POSTSCRIPT: On moving the car we found more green drops: the curse of the octopus had struck in the usual place - the leakback pipe from the front height corrector was split where it joins with the octopus main body.