Re: Diesel leak



I assume you are talking about the four high pressure feed lines from the injection pump to the injectors.  The following is true, if you have the standard Bosch Injector pump...

First, if you introduce air to the fuel system, you have to bleed at the injectors.

And now to the nitty-gritty...

There are two parts that seal the high pressure at the face of the injector pump, one is a fitting that is screwed into the body of the pump, the other is the high pressure flare-type fitting on the pump end of the injector feed tube.  

The nut on the flare fitting can be tightened.  If you do, be sure to get a wrench on the inner fitting to keep it from turning. For a flare fitting, the sealing surface is the metal to metal flare.  Teflon tape on the threads will do no good at all, and can only cause trouble. A TINY bit of antiseize only on the threads can help with tightening and removing later, but will not help with sealing. A danger here is if over tightening which can crack the tube, and that is a pain to replace.  If you loosen tubes to take them apart, clean everything around them fanatically before you break them open. 

One trick that can sometimes work for a stubborn leak here is to crack open one of these flare nuts while the engine is running, like you do at the injector end to bleed air.  Diesel fuel will squirt out, and if you have lead a good and pure life, it might flush out the tiny bit of dirt that was keeping the metal surfaces from sealing. I realize this is a pain to do on our boats because you have to be a double jointed contortionist monkey to reach it, even if the engine is off.

The fitting that actually screws into the pump body is a very different beast. Normally, these are only removed as part of an injection pump rebuild. My Volvo shop manual covers the process for removing the injection pump, but that is all.  Parts and service details are all Bosch. I don't have those.

 I have never had one of these apart, but based on similar fittings I would guess they are actually valves sealed at the base with a copper squash washer. Tightening them is not likely to help if the copper washer has been compromised, and teflon tape is an absolute "No" here.  Any parts here are Bosch parts, and I do not believe they are available from Volvo.  The good news is these pumps are very common and not at all specific to this engine. The name plate on the side of your injection pump should lead you to an online parts diagram and list.

Once you start messing with the inside of an injection pump, it becomes a very fussy job.  The tiniest speck of hard dirt can damage parts, clearances are very tiny. Many special tools are needed.  Most  small diesel mechanic shops send these out to specialty shops who have the tools and test bench needed.

I had a similar leak on a similar injection pump on my old boat.  After several tries on my own, I took the whole assembly to the rebuild shop.  Came back as good as new. 

Bill Kinney
SM160, Harmonie
Annapolis, MD, USA

---In amelyachtowners@..., <sailw32@...> wrote :

I have discovered that all three nipples screwed into the high pressure pump are leaking around the threads. I have a Volvo TMD22a . I could only get a wrench on the one on the end and tightened it a bit, but still leaking. I was told that I should reinstall them with teflon tape  around the threads. Would this be the recommended way to go? I am afraid a sealant may find its way into the system. Secondly, will I be able to bleed the air at the pump , or will I need to bleed the system at the injectors ?



SM Shenanigans

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