Yanmar 6LP issues

[Bruce]

I've been following the other thread and rather than redirect the thread I'll post this.

As most know I was a Yanmar dealer among other engine companies since the 80's. I saw some of the first 6LP's that came out and put a set in the 32 Luhrs open that I wrote an article on here many moons ago. I saw many 6LP's come thru the shop and sold quite a few and installed quite a few in repowers.

But here is my take when I first went to service school on them and at yearly dealer meetings. 90% of the "marine mechanics" out there are morons. That engine is a 4 valve per cylinder, overhead cam with a valve bridge. Most mechanics hardly can handle a two valve engine. While the service work was tedious, it was easy if you had the proper factory tools to secure the bridge when you adjusted them.

Unfortunately I ran into two major issues.
Number one was when the typical mechanic pulled the rocker cover, he hadn't a clue as to what to do even though the service manual was clear. I remember having to go around the room and help a good many of the mechanics during that first 6LP service school. My guess is many an engine never had the valves or bridge adjusted even though the owner got charged for it.
Second was that the machined nylon plate that held the bridge in place while the adjustments were loosened or tightened weren't used. Many mechanics used an adjustable wrench on the end of the bridge to keep it from twisting which stressed it. Its cast and they cracked doing it that way.

If you own a 6LP and need the valves adjusted make sure you ask your mechanic to show you his bridge securing plate. If he can't get someone else that has one.

Not one of the 6LP's I sold and serviced, or came into my shop as new boat engines and serviced ever had a valve or valve bridge issue. And we're talking a shit load.

If you did the proper maintenance, had the proper tools and did the recommended repair on the early on serial numbers and had the engine turn proper rpm to 3900, they are good engines.

And yes heads were tough to get on ones I did majors on back in the 2008 era because there were just not enough call for them. Hell I had trouble getting heads for most all their engines because I didn't see that hugh amount of majors come thru my shop. take care of em and don't overheat em and your good to go. You can also thank the EPA for making the engines go away which reduces Yanmars incentive to keep the parts flowing.

My opinion of Yanmar today. They screwed the pooch on their marine line big time. Also Yanmar USA and the Americans that run it are the biggest pile of scum buckets and the reason many dealers have turned their backs on them. They f'd over to many dealers trying to fatten their pay checks in Yanmar Japan's eyes'

I was just tired of seeing the guessing game on the other thread. Supposition and conjecture.




You may return to your regularly scheduled programming at this time.

[Navatech]

Nothing like a grease monkey who has actual experience with the specific (make and model) engine...

If I ever have a Yanmar issue I know who to call...

Cool tidbit... Back in the late 70's my late father was the purchaser's technical supervisor during the building of 4 feeder vessels... They had Yanmar auxiliary (generator) engines... As such he was invited to the Yanmar factory to be present during running in and testing... On one trip I was there with him... Got a full guided tour through the plant... An experience!... Especially as by that time I was already at the marine academy...

[Terry Frank]

Call Bruce a "grease monkey". I don't think so!

[Navatech]

Call Bruce a "grease monkey". I don't think so!

I call myself a grease monkey too :-)

[Carl]

Bruce, now that is the stuff you just don't know unless told by someone in the know.

So what should be basic maintenance can become the cause of catastrophic engine failure. Nice...

[CaptPatrick]

So what should be basic maintenance, can become the cause of catastrophic engine failure. Nice...

Unquestionably... The failure of almost everything is usually attributable to the lack of and/or improper maintenance, or abuse and misuse.

[Rickysa]

The failure of almost everything is usually attributable to the lack of and/or improper maintenance

boats, cars, planes, gardens, wives,.... :)

[coolair]

especially wives, which then in turn cause a catastrophic failure of your bank account... So I have heard!

[Bruce]

Carl,
Not doing the maintenance or doing it wrong can always lead to disaster. When machinery becomes more technical and surpasses the gas goes in here, spark goes in there which makes the propeller turn, most wrenches get left behind.

I won't even go into computer controlled and programming systems. All l'll say is deer in the head lights for most marine guys.

Remember Merc's diesel. Never found one dealer who did service on them.

The 6lp has two gaps. One between the cam lobe and bridge, the other between the bridge and valve stems of the two each exhaust and intake valves. Tedious? Can be but if you ever meet someone who specs turbine blades on jets ask em how tedious it is. Because you sure don't want to be piloting or sitting near it when it comes apart.

[Navatech]

Because you sure don't want to be piloting or sitting near it when it comes apart.

Nope... You REALLY don't want to be anywhere around a high speed turbine when it's grinding itself to bits...

During my navy days my surface combat station was a deck gunner (50 cal)... One time I'm just getting back to the ER, hadn't even yet removed my helmet or flack vest, on my way to let the Chief know I was back I was passing the right front engine and a grinding (think metal bits in a food processor) noise starts and I feel a tump in my back... Long story short, one of the turbochargers had "exploded"... Turbo housing itself had a chunk blown out... Many long hours later, after having removed the ruined turbo and installed its replacement I get around to putting my helmet and flack vest back in their proper place... While the damaged engine was being shut down I had thrown them somewhere in the ER... While folding the vest I suddenly notice some pieces of metal sticking in it... Deeply...

Still have those pieces of "shrapnel" like steel... Used to be blades of the exhaust side turbine... But for me still having my vest on I might be driving a wheelchair today...

[jspiezio]

Bruce- I am seeking your advice on the Yanmars one more time. This year I cruised them at around 2400rpm, just because it is a habit to take it easy on expensive pieces of equipment! This yielded 24 knots for me, with which I am happy. I occasionally pushed them to 2800/3000 pm, but rarely.

Recently I read that you need to run these engines at the higher rpm or they glaze the cylinders. Is this a real issue or is the way I am running these engines okay?

Happy Thanksgiving by the way to you and everyone else on the board (even those guys overseas who miss out on our Turkey Day).

[ed c.]

We run our engines anywhere from 3000 to 3500 most of the time. They now have 1800 hours on them, we troll but not much. I'm no where near being a mechanic, but you do have to run them up once in a while. Good Luck

[jspiezio]

Thanks ed. That seems to be the consensus. Hey,i just improved the cruise without having to test new props.

[Bruce]

Never saw a 6LP with glazing issues, but it does need to be run out from time to time. 3900 top rpm loaded makes a great 3400 to 3600 top cruise rpm.

If you don't need that speed all the time, its okay though.

Someone is more apt to develop carbon issues before they develop glazing given modern rings and cylinder treatment. Heat and compression fire off diesel. While some heat is developed just from the compression process, getting the cylinder combustion temps, not just engine basic temp, up into the proper range is a good thing.

[Charlie J]

bruce since we are on yanmars
what is your over all opinion of the on the 4 LHA engines 230
I have heard they were the best yanmar came out with.
happy thanksgiving to all

[jspiezio]

Thanks Bruce, now I have to go even faster. You guys really are great on here.

Enjoy Thanksgiving everyone of you.

[Bruce]

Charlie,
I think the 4LH 230 engine is a great engine built for durability. They and the 6LY series engine up to 350hp were good also.

[Charlie J]

thanks bruce
ive heard some big hrs on these engines with proper maintenance