Yanmar 6LP-STE Problem
Sorry for the long post but I figured that those of us that have this engine would be interested. These are postings from BoatDiesel.com (Excellent Website) Note the comment on Mobil 1 synthetic oil .
I have a 33' boat with twin 300 6lps. I dropped three exhaust valves in one engine and three exhaust valves were about to drop in my other engine. The following is a copy of emails, etc., but it tells the story. I'd be really interested in hearing any opinions or similiar problems. I know of at least 5 other engines that have had this problem.
It seems that there was some combination of exhaust valves sticking and valve keepers shearing off. (The shoulders were sheared off of many valve keepers.) Keep in mind that I had this problem in both engines. Three exhaust valves were close to dropping in my good engine, and three did drop in my NOW bad engine. I also found a broken valve spring.
I have a new engine on the way, but so far Yanmar has not been willing to offer any assistance.
Yeah, the engine is a few years old, but to me, this is clearly a factory defect. Valve keepers should not shear off at 2000 hrs.
As I mentioned in earlier posts, Yanmar was willing to send me new valve seals (for free) because the ones I had may have been (and in fact are) defective, but would not cover installation. A Yanmar rep eventually talked me out of changing the seals because he said it was an occasional problem that occurred under very warm (tropical) conditions and with 2000hrs, I'd be ok.
I'm aware of the pleasure boat rating for the 6lp. Unfortunately, Yanmar did not tell us that 4-5 years ago when many six pac charter boats up here went to them to get away from Volvo Penta. In strong terms, Yanmar claimed to be the best for our application.
When I mentioned this to a Yanmar rep on the phone, he hesitantly told me that "recreational" includes six pac charter vessels. This was a few weeks ago when we were discussing the valve seal condition. Now many of the Volvos are lasting 5-6000hrs. OUTLASTING my Yanmars by far.
My primary concern is to get up and running. I am not at all happy with Yanmar's position so far, but we will see what happens. I was also told a while back by a certified Yanmar guy to run the engine at 3200-3400rpm. NOT the 3600rpm as the engine is rated for. He said that in order to last, that engine NEEDS to run 600rpm less than the WOT rpm.
This pretty reputable guy told me that I could run them at 3600, but only if I wanted to buy a new one every year. The "recreational use" term has made me wonder about the quality of these engines. In our application, we are running exactly like a weekend boater, only we do it every day. These engines are not running continuously at low rpm, etc., etc. In fact, our maintenance schedules are much more rigid than the average recreational boater and we operate as the manual and mechanics tell us to.
Am I to believe that recreational use means that these engines are not intended to last very long? I suppose that the average boater may run his engine for 200hrs/year. I also suppose that at that rate, the engine may last 10 years. Maybe after having the boat for 10 years, the average guy would think he got a good deal.
Is this a 2000hr motor?
I had a similar failure just last week with catastrophic results; the cylinder head is toast and probably the block as well. The valves dropped in cylinder number 1; however; several other valves were ready to go. The valve retainers showed the same type of failure as described in an earlier posting. There was no warning, no noise, and no reduction in power prior to the failure. The engines were well maintained with just over 400 hours on them. The failure occurred in the starboard engine; however, the port engine appears to be fine.
I was just north of Vancouver Canada, traveling from Washington to Alaska when the engine blew. The Canadian Yanmar distributor and the local Yanmar dealer (Marine Systems in Mosquito Creek) have been good to work with, and Iím hopeful a resolution is quick in coming.
Good news: after appropriate due diligence including a visit by the Canadian Yanmar distributor, it was determined a long block replacement under terms of the extended warranty was in order. Additionally, Yanmar is replacing the valve seals on the second engine, also under warranty.
The servicing dealer (Marine Systems) and the Canadian Distributor (Land and Sea) were very helpful during this process. Since we were on vacation when the failure occurred, we continued to live aboard the boat. The dealer provided us with moorage space, power, water, and marina amenities. When working on the boat, the mechanics always left it clean and orderly.
Yanmar took a situation which could have been very ugly, and turned me into Yanmar fan. Yes, I had appropriate documentation regarding dates and services performed, and yes, I had the assistance of a dedicated servicing dealer, but the bottom line is Yanmar came through.
So is there any preventative measures that older 300 owners could have performed to prevent these valves from dropping?????
I'm still waiting for Yanmar's response to my situation. So far, I'm not impressed. This does appear to be a defect. I would check your valve keepers as regularly as changing oil. I'll post more as it develops.
Unofficially, Iíve heard that changing to the latest valve seals and using synthetic oil solves the problem. Also, as mentioned in other posts, we should minimize low speed operation; tough to do in congested areas and lumpy seas.
When coming down from cruise, Iíve always dropped rpmís slowly, but I donít know the best way to build power after a period of slow running. Is it better to clear the engine by increasing rpmís in neutral for a short period, or keep the engine under load?
Itís been two weeks since mine blew and Iíve yet to get the go ahead on warranty repair. Yanmar havenít said ďnoĒ, but neither have they said ďyesĒ. Part of my problem is that the engines sat on the shelf for two years prior to being delivered to my builder. Both the builder and the original distributor are now out of business. So far Yanmar has asked for pictures of the engine, head on and head off, showing the damage, as well as pictures of the hour meters, serial number tags, vessel documentation, and ships log, to verify the in service date.
These engines ran beautifully, started easily, were smooth, powerful, light, and relatively quiet. There was never a hint of impending failure
Just wondering where you heard about using synthetic in the engines? From a yanmar rep or other. Benn looking into using it myself as I work at a mercedes dealer and have access to mobil 1 at a good price.
Mobil 1 synthetic oil was a disaster in aircraft engines and was taken off the market due to engines seizing and aircraft crashes. The synthetic oil was deterimined not capable of carrying lead and other deposits in suspension resuling in coking and carbon build up in piston rings. There may be a similar problem contributing to valves sticking and breaking in the high performnace Yanmar engines.
The best way to get Yanmar to come forward w/ a solution to this issue, is to keep the topic active on this site. Keep the emotion out, have good records and be sure all of the required maintenance and owner obgligations can be fully documented. Also, no rumors or "I heard", "he said", "they said".
Believe me, Yanmar and the rest of the players in this marine market watch this site daily.
ANON, for obvious reasons
Am having a sea trial today of a 26' SHamrock with the 6lp dte Yanmar, 250 hp version. Yanmar tech is looking over the engine this morning - should I alert him to valve issue and is it easy to identify if a problem is looming? Thanks
Anyone have any experience changing out the valve seals? Is this an expensive repair or something relatively straight forward?
If there is one thing I learned about the 24 Valve 6LP at school, it's that you definitely want to be sober when taking one apart and then reassembling it.. This engine has as many monkey motions upstairs as an Indy engine
You mean this isn't like my old 235 cube 1956 Chevy 6 cylinder????? All kidding aside, I appreciate your reply...I wouldn't dream of doing it myself......I guess I should have asked is this an expensive preventative repair if I have my local Yanmar Service Dealer do it?
Greg the problem as far I'm aware has only been with theb 24 valve 300hp's not the 12 valve 250's
Thanks David - The Yanmar tech that gave my motor the once over confirmed that this was not an issue w/ the 250 hp motors. Regards
i am sorry about my english, i live in venezuela. i have the same problem with he exhaust valves. the last year port engine 400 hours he losses two exhaust valves. i had to repaired my self (the valves did not drop off) and the only difference was the valve seals that supoose to solve the problem, i had changed the valve seals in both engines. This year i was in the Miami boat show and contact the yanmar people(Mastry) and they recomend to me to low the propeller pitch to get 4000 rpms instead of 3800 wot. I did that and get 3950 rpms and 3600 in cruise speed. the last month. the other engine (with the new valve seals instaled and 570 hours) had the same probem, but this time the valve drop off in, causing severe damage to the piston 6. both engines were always with synthetic delvac 1 mobil diesel oil. it suppose that is the best diesel oil that i can use. I suppose that the problem is the acomulation of carbon in the valve guides getting stick. I dont know how to solve the problem and the yanmar dealer in Venezuela dose not know too. the two problems occur after a complete fishing trolling day.
It is very difficult to solve such a serious issue without factory input.. With the valve problem on this engine coming to light more often, I'm sure Yanmar is looking into the long term solution.. This engine is developing upwards of 70 HP per liter and the stresses on every component are well above those for its automotive counterpart/derivative.
The first time I heard of these issues I attributed it to a "random failure", something that just happens sometime.. Now with about a dozen or so that I have heard of, obviously this is an issue that needs to be dealt with at manufacturing level... It's too bad it occurred using Mobil 1, as I know from experience that this oil is truly a cut above.................................Hopefully, someone w/ closer connections to the factory will offer some assistance for you, and other owners, in solving this problem by offering something more than not "trolling" and then "accelerating" , or something along those lines............................................
I sent Yanmar (Georgia) a letter a few weeks ago. I still have not heard back from them, nor have I heard anything from my (north) west coast distributor. It is very interesting to hear that this has occured in an engine with the new valve seals.
according to Yanmar tech bulletin MSB 02-049 July 3rd 2002 changes including new exhaust valves were made on 6LP-STE & STZE models from s/n51640 onwards. The bulletin also shows a diagram from the Yanmar parts catalogue showing exhaust valve stem seals with diferent p/n as a "repair part". All 6LPA's have these parts fitted
2002 270 Mackinaw
Warwick (Narragansett Bay), RI