Author Topic: Sheared Monark pintle  (Read 1988 times)

May 23, 2021, 09:35:14 am

wil892

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Sheared Monark pintle
« on: May 23, 2021, 09:35:14 am »
About 20 minutes into running a set of rebuilt injectors with new Monark nozzles my engine started nailing. I shut it down almost immediately and was only run to identify which injector was at fault. I don't think any damage was caused as it was only idling.

Anyway, I've disassembled the injector to find that the very tip of the pintle has literally sheared and stayed inside the nozzle. Looking at the breakpoint it's lucky this didn't exit the injector into the cylinder.

Has anyone seen this failure before? I can't figure out what would have caused this. I'm getting them all rebuilt with Bosch now as I can't trust the rest of the nozzles

Nozzle by William Harper, on Flickr

« Last Edit: May 23, 2021, 02:06:09 pm by ORCoaster »


1991 Golf MK2 GTD

Reply #1May 23, 2021, 02:06:50 pm

ORCoaster

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Re: Sheared Monark pintle
« Reply #1 on: May 23, 2021, 02:06:50 pm »
Have not seen that happen before.  Maybe poor machining when built? 

Reply #2May 25, 2021, 09:25:15 am

sgnimj96

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Re: Sheared Monark pintle
« Reply #2 on: May 25, 2021, 09:25:15 am »
No personal experience with this, but great question.   Monarch nozzles are generally better than bosch (india, brazil, china).
I'd get another monarch to replace the one.   Could just be something got (or still is) in the fuel system and would have damaged any nozzle.

example (from web search):
Blown Injector Tip
It is possible for an injector to blow a tip. This is most frequently caused by air or water contaminating the fuel and affecting the pressure buildup. Some injectors are more sensitive to contamination than others, namely the common rail injectors, so it's important to not only diagnose the blown tip, but the contamination cause as well. Otherwise, you'll continue to have issues with your injectors, even after you replace them.
81 Scirocco 1.6D (conversion)    86 Gofl 1.6D      2003 Golf Tdi   1985 300TD

Reply #3May 25, 2021, 02:43:11 pm

libbydiesel

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Re: Sheared Monark pintle
« Reply #3 on: May 25, 2021, 02:43:11 pm »
There is always some air in the injectors and metal lines when you first go to start it after the lines/injectors being off.  There is no way to avoid that. 

Reply #4May 26, 2021, 05:06:34 am

wil892

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Re: Sheared Monark pintle
« Reply #4 on: May 26, 2021, 05:06:34 am »
I had an initial issue with the injection pump which had build up some corrosion and stuck one of the mechanisms.

This is result in some debris entering the injectors. The pump was rebuilt and tested at Bosch specialist and injectors were checked and tested.

'm really surprised that debris would actually result in fracture rather than just a stuck injector. Looking at the break point it is just below the sealing chamfer.

I would love to run these Monark nozzles, and certainly the engine sounded absolutely lovely when running properly but I can't risk this happening again and taking out precup or something if I was on the motorway.

Obtaining replacement Monarks is also very difficult, as these are the GTD DN0SD274 nozzles for the 80hp engines.

Please let me know if anyone has a spare set though!
1991 Golf MK2 GTD

Reply #5May 26, 2021, 02:22:51 pm

sgnimj96

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« Last Edit: May 26, 2021, 09:47:31 pm by sgnimj96 »
81 Scirocco 1.6D (conversion)    86 Gofl 1.6D      2003 Golf Tdi   1985 300TD

 

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