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Tspringer · 11-02-2009, 10:50

I am heading back down to St. John in early March to tackle some maintenance on the engine in our 1981 Stevens 47.

The engine is a Yanmar 4JH2HTE. 75hp turbo diesel with approximately 3800 hours on it.

This engine was installed in 1992. She runs well, but does blow a bit of whitish smoke.

I really do not know what to think of this whitish - light grey smoke. It is not excessive and is present more when the boat is cold than when fully warmed up but even when warm it does do this smoke a bit. I suspected compression, and I guess it could be, but the engine does start immediately when cranked even when cold. By immediately, I mean that when the key is turned the engine turns over no more than for 1 or 2 seconds before firing and running smoothly. Its probably just condensation.... but I am a worry wart.

Regardless, the engine definitely needs a valve adjustment. Also, a number of the rubber hoses on the engine are showing dry rot and need to be replaced. The engine itself has a fair amount of surface rust that needs to be ground off, treated and then repainted.

My plan is to strip off as many hoses and ancillaries as possible (including the starter, alternator, most wiring and most hoses and such) so I can get at the entire engine. I will then sand and grind off all the surface rust, clean everything thoroughly, treat the metal and repaint it all. Then after adjusting the valves and doing any other maintenance required I will put it all back together again with new hoses and gaskets and anything else required. I will also be replacing any worn wiring and worn connectors.

So....

What parts should I replace? Where is a good place to source such parts? I have never adjusted the valves on a Yanmar diesel... but I have on lots of pushrod activated overhead valve cars, my understanding is that the Yanmar uses screw adjusters so how hard can it be?

Any Yanmar techs on the board? I though I read on here once that a good Yanmar tech posted frequently who is here near Lake Lanier in GA but I cannot find the posts after searching...

We will be bringing my boat back from St. John to Savannah, GA in May so I need to make sure the engine is in top shape before the trip. All tips and suggestions are greatly appreciated. I did just change the oil, filter and fuel filters in December when last on the boat.

Terry

**GordMay** · 11-02-2009, 11:38

You should download the Yanmar Service Manual, for the 4JH series
http://sagaforumet.com/yanmar-manual/4JHE/manual.pdf

Chapter 2 specifies the valve clearance at 0.2mm or 0.0079".

Charlie · 11-02-2009, 12:02

Never Mondday is a god source for info on Yanmar diesels.

DeepFrz · 11-02-2009, 13:55

Home

Link to never monday's website.

cdennyb · 11-02-2009, 15:13

Gord May;

Sir, that link is only a 2 page doc and thru a little digging I was able to go directly to the home page and find the link to the technical page which has several other manuals in both Norweign and Swedish, as well as a couple said to be in English but if you download them, only one is complete and the other is only 2 pages, obviously they had some problems posting the whole doc.
Just thought you'd like to know.

**GordMay** · 12-02-2009, 12:31

The link I provided takes you to the front page & index. Click on each (blue) chapter heading, in the index, to get the chapter content.

cdennyb · 12-02-2009, 12:47

I stand corrected. It is now clear to me that it was a link to a two page document that was an index of links to each section. I mearly looked at the 2 pages of the pdf and expecting a significant number of pages decided it was an incomplete upload. I deducted that it was a front cover and table of contents but the second page (with the individual links was too small for me to see at first.)
My appologies.