Yanmar 4JH3E Valve Stem Seal Replacement

[feudalkaos]

We had some water get into one of the cylinders a while back. I was able to get all of the water out very quickly by pulling the injectors but it definitely tried to compress a couple times.

Since this happened the engine still runs very well with no noticeable loss of power or smoking so I think the valves are probably okay but I am getting a bunch of black carbon on the transom after startup and I have noticed more oil consumption then normal.

From this I have concluded that it may be a valve stem seal that needs to be replaced. I have read that this can be done without taking the head apart so I am looking for anyone with advice on the matter.

I understand that some people have used compressed air into the cylinder via the injector port to keep the valves in place while removing the springs. I have also heard that you can just put the cylinder at TDC which will leave very little clearance between the piston and the valve so the valve will not be able to fall into the cylinder. Anyone with experience with either of these approaches?

I prefer the TDC option because I can keep the fuel injectors in place but I wouldn't feel comfortable without some first hand knowledge that this would work on this engine without issue.

Also, does the retainer parts need to be replaced when pulling them off of the valve stem?

Thank you for the feedback!

[Wotname]

I think your conclusion is wrong. A failed valve stem seal will not cause enough oil consumption to get a black transom. Typically leaking valve stem seals give you a good puff of smoke at start up and then not be noticeable.

However the valves won't drop very far at TDC so you could use that approach if you wish

[feudalkaos]

Originally Posted by Wotname

I think your conclusion is wrong. A failed valve stem seal will not cause enough oil consumption to get a black transom. Typically leaking valve stem seals give you a good puff of smoke at start up and then not be noticeable.

However the valves won't drop very far at TDC so you could use that approach if you wish

Any suggestion as to what could be causing the carbon? From what I can tell it would have to be either the valve stem seal, a bent valve stem guide, or bad rings on a piston. Other thoughts?

I am leaning toward the valve stem seals or valve guide because the piston rings would likely come with some performance hit which I am not seeing.

[Jammer]

What I have to add to this conversation is that, I have never encountered a situation where the useful life of an engine could be meaningfully extended by replacing valve seals without removing the head.


I've tried once or twice with the compressed air trick and special spring compressor tools and it was a lot of zarking around with poor results on an engine we finally figured out had plenty of other problems anyway. Maybe your situation is different but....


...I'd take a close look at the age in years and hours of what you're working with and think in terms of either a valve job or repower.

[Compass790]

I tried to post but lost it earlier.
My gist was same as Wotname & jammer, think you have other issues than v/v stem seals. My guess is a ring problem.
If you have done a compression check could still be an oil scraper ring issue.
Another guess is broken ring trying to compress water.
But check pushrods as well if its a pushrod engine

[Wotname]

Originally Posted by feudalkaos

Any suggestion as to what could be causing the carbon? From what I can tell it would have to be either the valve stem seal, a bent valve stem guide, or bad rings on a piston. Other thoughts?

I am leaning toward the valve stem seals or valve guide because the piston rings would likely come with some performance hit which I am not seeing.

Possibly from a carboned-up exhaust system or mixing elbow????

[feudalkaos]

The engine is 2001 with 1450 hours. Since it is a Yanmar 4JH3E I believe it should have many more hours of life left on it. There is no noticable issues other than the carbon on the transom and a higher oil consumption.

It still appears to have full power across the entire range and does not appear to smoke expect on quick rev up.

It is hard for me to believe there is something significantly wrong with this engine without some other symptoms but perhaps I am missing something.

I have not yet done a compression check but have been considering it.

[Wotname]

Is the prop and bottom clean?

This can cause these symptoms.

[feudalkaos]

This has been happening for a few months and we just did about 600 miles. Many of those miles were on a clean bottom and some not so clean. We do a bottom cleaning every month or so.

The carbon seems to mostly appear just after start up.

[jakkum]

I tried to compress water with a Lister JP3.
That resulted on a bent and so shortened conrod.
So also loss of compression
No black smoke that I remember but bad runnong
Also, the bent conrod broke a bottom part out of the cilinder liner.
So it was quite some damage.

[feudalkaos]

Originally Posted by jakkum

I tried to compress water with a Lister JP3.
That resulted on a bent and so shortened conrod.
So also loss of compression
No black smoke that I remember but bad runnong
Also, the bent conrod broke a bottom part out of the cilinder liner.
So it was quite some damage.

Thanks for the reply.

I assume it was pretty noticeable after the incident correct?

In my case, I have done around 180 hours on the engine since the water situation. First start after it had a bit of smoke (white if I recall correctly) but that didnt last long. After getting the water out I filled the cylinder with oil and fuel to keep it from corroding so I attributed that smoke to the burn off of that mix.

The water had gotten into the cylinder via the mixing elbow because my PSS Shaft Seal had been connected to the raw water pump and was trickling water in any time we leaned. I noticed the water issue when I went to start and it did not. I thought it was a bad starter because it only turned once or twice. I know it tried to compress some amount of water a few times but not at running speed so I have been hopeful no major damage was done and so far I have had no major symptoms that would suggest it did much damage.

[LeaseOnLife]

A reasonably easy job would be to remove the injectors again and

• have the injectors tested by a diesel shop (bad injector tips do cause smoke)
• and at the same time test compression and if any differences between cylinders are observed, try to locate the leak by testing the compression "wet" with some oil around the rings.

You likely need a special adapter for the compression test, the typical autostores probably don't have that. It may pay to bring a Yanmar tech for a few hours.

[feudalkaos]

Originally Posted by LeaseOnLife

A reasonably easy job would be to remove the injectors again and

• have the injectors tested by a diesel shop (bad injector tips do cause smoke)
• and at the same time test compression and if any differences between cylinders are observed, try to locate the leak by testing the compression "wet" with some oil around the rings.

You likely need a special adapter for the compression test, the typical autostores probably don't have that. It may pay to bring a Yanmar tech for a few hours.

Since starting this thread this is the direction I am now leaning. I have found compression test fitting that is designed for Yanmar engines and a reasonable cost. According to Hoyetractor this part should fit my 4JH3E.
https://www.hoyetractor.com/PROD/CT-TNV-KIT.htm

[Ericson38]

Originally Posted by LeaseOnLife

A reasonably easy job would be to remove the injectors again and

• have the injectors tested by a diesel shop (bad injector tips do cause smoke)
• and at the same time test compression and if any differences between cylinders are observed, try to locate the leak by testing the compression "wet" with some oil around the rings.

You likely need a special adapter for the compression test, the typical autostores probably don't have that. It may pay to bring a Yanmar tech for a few hours.

This is great advice.

Also, is the turbo spooling up like before ?

Did any water get into the turbo exhaust turbine blade disc, causing a sticking turbo ?

I would also, if you have the opportunity, run a quart of Risilone or Marvel Mystery oil in the crank case, for a few hours, then drain and refill with Yanmar branded 30W oil, then the compression check by a tech.

You will need a special adapter for the compression test, hence a tech, unless you can obtain one of those.

[feudalkaos]

Originally Posted by Ericson38

This is great advice.

Also, is the turbo spooling up like before ?

Did any water get into the turbo exhaust turbine blade disc, causing a sticking turbo ?

I would also, if you have the opportunity, run a quart of Risilone or Marvel Mystery oil in the crank case, for a few hours, then drain and refill with Yanmar branded 30W oil, then the compression check by a tech.

You will need a special adapter for the compression test, hence a tech, unless you can obtain one of those.

Mine is a NA motor so no Turbo.

I will consider the treatment option. I have considered doing this also.