Is this a problem? Beta 43

[robtheplod]

Hi All

 

I did a service on the engine today and whilst running it to check for leaks i noticed what looked like air bubbles coming through what looks like the edge of the screw thread of one of the injectors? (i think this is right?). Not much but noticeable.... is this of concern?  not sure on best course of action if any?  thanks!!

 

 

[BEngo]

That looks like a leak round the injector body.   If left it will get worse and may damage the head.   The cure is to remove the injector, clean up the injector face and the bottom of the hole where the injector goes,  and refit, renewing any sealing washers.

Depending on the age of the engine it might be worth removing all the injectors and having them serviced whilst you are disturbing the pipework.

N

[Tony Brooks]

As no on else with better experience of Kubota has replied I will give my thoughts.

 

I think there are three possibilities, all of which depend upon the spillage of liquid or condensation.

 

The injector nozzle can get very hot so:

That may expand air trapped in the threads that expands and is expelled upwards through liquid that has collected around the thread. This should stop after the engine is up to temperature or when the liquid has evaporated.

It could be liquid that has worked down the threads boiling and bubbling out upwards. This again should stop after a good run.

 

It might be that the seal between injector and cylinder head is leaking slightly but as I don't know the Kubota arrangement I can't suggest what and how. I don't think it will do any harm in the short term but might if left indefinitely.  There may be a taper metal to metal seat and if so removing the injector,  scrupulously cleaning both halves of the seat, and refitting to the correct torque may be all that is required. It may involve one or more copper washers and in that case removing the injector, cleaning the steel faces, fitting new washers, and tighting to the correct torque is likely to work. In either case ignoring it for a long time just might burn a slot in the seat so it would never seal.

 

I would suggest that you give it a good run and see if it cures itself. In fact it might even stop as the engine warms up and expands. It this seems to be the case it would be a good idea to tighten it to the correct torque.

 

Happy to be told this is rubbish by one of our engineer members who is working on Kubotas.

 

BEngo posted as I corrected my post.

 

 

 

Edited October 24, 2021 by Tony Brooks

[MtB]

On the other hand it might, if left, just seal itself up with come carbon!

 

It probably won't though....

[robtheplod]

Thanks all... The engine wasn't too hot as it was just run to warm up the oil prior to servicing. I'll keep an eye on it and monitor after its been running for a prolonged period, thanks so much for all the helpful replies, very much appreciated.

[robtheplod]

On 24/10/2021 at 10:07, robtheplod said:

I now have a video of this so hope that makes diagnosis a little easier...

 

[Tracy D'arth]

If you clean the filth off the top of the head you may well find that this is water boiling off from under the oil that is puddled around the injector.

[robtheplod]

4 minutes ago, Tracy D'arth said:

If you clean the filth off the top of the head you may well find that this is water boiling off from under the oil that is puddled around the injector.

Thanks Tracey, yes i do need to keep on top of my cleaning (!!).... i do see the bubbles immediately after starting from cold so would that indicate otherwise?

[MtB]

Did Beta build the engine out of focus, or is it a dodgy camera?

 

I'd be inclined to ignore that leak. The engine will prolly be ready for a rebuild before any serious consequences occur. 

 

 

[Tony Brooks]

The video seemed to indicate the bubbles were from the leak off banjo, not the injector thread in the head.

 

If it is from the head it will not hurt to take the injector out and clean all the mating faces and tapers (I think the body might seal on a taper), renewing any copper washers and then use a torque wrench to re-tighten.

 

Injector bodies tend to get hot fairly quickly on start up but the rest stays cool.

[robtheplod]

4 minutes ago, Tony Brooks said:

The video seemed to indicate the bubbles were from the leak off banjo, not the injector thread in the head.

 

If it is from the head it will not hurt to take the injector out and clean all the mating faces and tapers (I think the body might seal on a taper), renewing any copper washers and then use a torque wrench to re-tighten.

 

Injector bodies tend to get hot fairly quickly on start up but the rest stays cool.

fab thanks so much Tony!

[Cheshire cat]

The only other question I can think of asking is have you had the fuel filter swapped out recently. I'm wondering if someone cracked open the injector from it's seat to attempt to bleed air and then didn't tighten it sufficiently.

[Tony Brooks]

You would only crack the injector from its seat if the whole thing turned when you tried to loosen the injector pipe, and if you did that the leak off pipe would be bent.

[robtheplod]

46 minutes ago, Cheshire cat said:

The only other question I can think of asking is have you had the fuel filter swapped out recently. I'm wondering if someone cracked open the injector from it's seat to attempt to bleed air and then didn't tighten it sufficiently.

Yes, but I did it, and no issues there....

[magnetman]

Suspect the big end has gone. 

[MtB]

43 minutes ago, magnetman said:

Suspect the big end has gone. 

 

Ah, good call. Regrind the crank and replace all the big ends and I bet that leak will disappear. 

[Tony Brooks]

18 hours ago, robtheplod said:

fab thanks so much Tony!

 

If you do decide to pull the injector all four injector pipe unions will have to come off at the injectors AND the other ends loosened at the pump so you can allow the pipes to "flop" clear of the injectors. On no account bend them with the pump ends still tight, that way leads to pipe/olive failure later.

 

Then remove the spill rail so you can get a deep socket on the injector.

 

I would use new soft washers on the leak off pipe but if you can't heat them to red hot and let cool or quench in water.

[robtheplod]

8 hours ago, magnetman said:

Suspect the big end has gone. 

Really?

[MtB]

38 minutes ago, robtheplod said:

Really?

 

It was a joke.

[robtheplod]

1 minute ago, MtB said:

 

It was a joke.

phew..... don't forget I'm mechanically challenged!

[Cheshire cat]

18 hours ago, Tony Brooks said:

You would only crack the injector from its seat if the whole thing turned when you tried to loosen the injector pipe, and if you did that the leak off pipe would be bent.

 

A novice wouldn't know this until they tried.

[ditchcrawler]

8 hours ago, MtB said:

 

It was a joke.

I thought you had got a job with a well known boat breakdown company