middle aged yanmar 4jhe idiosyncrasies question

[waternwaves]

older hunter/ 4 cylinder yanmar powered question.

many would tell me to go to cruisers or engine forums for the answer to this,(as many answers as there are questions) however I am going to ask it here.
I have a 4JHE "(non turbo 4 cylinder) yanmar in my 85 H40, I have cruised by others boats with yanmars, tho few of this vintage....total hours is in the 5K plus range I am guessing, tho the meter only shows 2K(perhaps previous servicing folks installed the meter later) anyway.
like most yanmars the only time I dont notice a fair amount of smoke is under full power. 40 hp at 3500 rpm. lower speeds result in noticeable smoke, starts blue turns grey-after warming upbl. slight sheen on the water surface when idling, Fuel is sweet, little bit of black soot that has to be cleaned off the transom every trip. doesnt consume lube oil. (1/2 quart after 80 hours). I can run it from a clean gallon container of fuel and no change in smoke properties. (not quite an m1Abrams in defensive smoke generation mode but far more than seem necessary for a 1980's engine..... I guess
I know about the leak down into the cylinders after shutdown, and having all that extra carbon to remove when the engine gets hot again, I am aware that these engines have mechanical fuel metering, (I ha ve spent the requisite hours dissassembling with the good yanmar manual) they are finicky. to get enough fuel at full load makes them run a little rich at lower 2200 rpm or so, the little beast is reliable. seems to start every time, shakes like a little monster at 900 rpm, can get to 3500 rpm with the current prop, and the boat does a little over 7-1/2 kts. fuel Inj timing checks out per mechanical markings,
Compression on this engine is still strong,

is just me?.....or does this thing just smoke more than a perkins, atomic, bmw, or any other diesel that I have ever played with.

does everyone elses smoke too much at low to medium rpm's?

 

[Guest]

4JH

Our 1991 model P42 came equipped with a 4JH2-TE that has acquired a little over 1,400 hours of use. It had 635 hours when we took ownership in 2002. It always starts any time of the year, never smokes regardless of load or RPM and does leave a small amount of soot residue on the hull around the exhaust through hull after several months of operation.

My only thought is whether your engine has any kind of fuel air mix adjustment. Perhaps it is running a bit rich. I know that older commercial diesels tend to smoke more than newer ones, especially when cold or under load.

Terry Cox
Shelter Bay, WA

 

[Rick D]

4jhe

I have 2100 hours on an early 90's vintage. t smokes on start up and until it warms up. It goes away after it warms up. It will leave exhaust residue after extended motoring. However, I don't believe it smokes any more or less than a Perkins or Universal. Probably less than the Volvos I have seen. Oil consumption might be about the same as yours. Don't know if that helps you or not.

 

[Vinny]

I have a 4JHE "(non turbo 4 cylinder) yanmar in my 85 H40,

seems to start every time, shakes like a little monster at 900 rpm,


does everyone elses smoke too much at low to medium rpm's?

Waterwaves,

The 4JHE in the 40 Legend is detuned a bit (44 hp vs 54 hp) due to the smaller exhaust that was put on by Hunter to shoe horn it into the rear part of the engine compartment. The mixing elbow on our engine is from the the 3GM series and not the same as the one that the 4JH was designed to use. I have confirmed this with Torressen Marine and Mack Boring, who supplied the engines to Hunter. Permission was granted by Yanmar to make the exhaust change for this installation on the H40's. The interesting part here is if you bought a new engine and did the same thing to it that would void the warranty. go figure. It is smaller in diameter by an 1" and that could contribute to some build up if the engine isn't run at 2,700 (80%) for most of it's life.

Do a valve adjustment first. A bad valve adjustment means bad valve timing which means improper fuel air mixture. Remember the manual gives the adjustment in mm not inches. I don't have mine in front of me but an example is .02mm is not .20 thousandths it is .0079 thousandths. .008" is close enough. .010" should not be able to slide through. You are not strong enough to force it through, you can not compress that valve spring. So if .010" goes through, that valve is to loose. I stress this because the valve timing is effected by loose valve settings as well as the noise and wear factor.

Next is the shake at 900 rpn. You have done a compression test so you know that is good. That only leaves a couple of other things. I would take all four injectors out and have them tested and or rebuilt. Just a word of caution I had a problem with a shop in New Bern that after rebuilding them wanted more than what they would have cost new. We, after a long discussion resolved that issue. If I remember correctly they are about $155 each new from Torressen Marine in MI. A bad injector could be wetting one cylinder down with to much fuel and be the smoke issue.

If you are going to try to find just the one injector then start the engine let it get to temp and set it at 900 rpm or the shake mode. While it is shaking, at the injector, brake open the fuel line like you do to bleed out air. The one that doesn't effect how the engine runs when you open it is the bad cylinder. Now all there is to do is figure out if it is the injector or the pump it self. You could move the injector from one cylinder to another and if the problem moves with the injector then it is the injector, if the problem stays in the same cylinder it is the pump. But after 4-500 hours the injectors are probably having spray pattern problems anyway. So cleaning and testing them is not a waste.

Good luck.

 

[Bill Roosa]

unburned fuel

agree with Vinny check the injectors
Everything you discribe is unburned fuel. That comes from not enough air in or not enough exhaust out or too much fuel each injection cycle. You probably don't have an intake air problem but the detuned exhaust or a bad injector could be the problem

 

[waternwaves]

The vibration is a function of the natural frequenc0 y of the surrounding cabine companionway step assemblies. vibration meter does not show increase defelection at that RPM, (less than .001" (just try and find a non vibrating surface to mount that to, So ended up checking at the motor mounts.

swapped injectors, still smooth on acceleration, no change, The end two are bears to get out.

As far as HP ratings.

for my particular engine, I will have to disagree slightly on the hp designation. all the marine info I find for 1983 -1985, including my two manuals shows the orignal 4JHE as the little brother of the series. examination of the only other marine 4 cylinder engines offered at that time were turbos, most with different compression,

jh2's didnt come out till 89 or so, jh3 later, and those were all turbos.

I checked with my dealer on the marine and the tractor versions of the 4 cylinder, and they found the 4g, L series, LV series and the like as well as marine offerings jh, jh2 etc in 85, All those were different configuration. So I believe if we are to stick with the numbers for he marine engines, I am fairly certain that this is a stock 4JHE with the correct applurtenances hanging from it.
(except the 105 amp alternator upgrade that I have to find a place to rewind, I have a few turns shorted and it wont get above 13 V) So if anyone has a low cost 105Amp alternator for this engine sitting around taking up space on their shelf, I am probably going to send some benjamins to get that repaired or replaced)

As far as the elbow discussed, it matches the yanmar parts catalog number & marking for diameters and has not been reduced. I probably have more room for the full elbow because of my racor panel mounted behind the engine. As far as installing a smaller elbow, My guess is that might have been done by some to free up some space for racor/filter equipment and the like. my mixing elbow is different than the turbo versions of course.
Mine is the 3" (76mm)as shown in the diagrams supplied with the engine.

the valve adjustment/timing you talk about seems to be the likely next candidate for me to check. I will read up on that. i had been told by another (at tri county diesel) that yanmars rarely see much valve wear/change. It seems strange tho..... because I still have very good compression, and if a valve was damaged or not seating, then compression would be off on a cylinder. hmmmmm

Thankyou all for all for the tips, I will continue to update until I can minimize the last of this oil sheen and have the smoke minimized.

 

[petersea]

another vote for the injectors.

 

[Vinny]

As far as HP ratings.

As far as the elbow discussed, it matches the yanmar parts catalog number & marking for diameters and has not been reduced. I probably have more room for the full elbow because of my racor panel mounted behind the engine. As far as installing a smaller elbow, My guess is that might have been done by some to free up some space for racor/filter equipment and the like. my mixing elbow is different than the turbo versions of course.
Mine is the 3" (76mm)as shown in the diagrams supplied with the engine.

the valve adjustment/timing you talk about seems to be the likely next candidate for me to check. I will read up on that. i had been told by another (at tri county diesel) that yanmars rarely see much valve wear/change. It seems strange tho..... because I still have very good compression, and if a valve was damaged or not seating, then compression would be off on a cylinder. hmmmmm

Thankyou all for all for the tips, I will continue to update until I can minimize the last of this oil sheen and have the smoke minimized.

First off my engine is a 4JHE as ID'ed by the plate on its side. The exhaust water mixer for the 4JHE is a straight stainless piece of which mine is not. The one on my engine is in fact the same as the one on a 3GM which I had on another boat. It is only 2" and not 3" as the engine was designed to have. I am the second owner on my boat and the guy that owned it before me couldn't spell wrench least of all use one so this is the way the boat was built by Hunter and it is not modified. The change in the engine was approved by Yanmar and verified by the folks at Mack Boring (they supplied Hunter with the engines).

As far as the valve adjustment goes I never said you had a burnt valve. You missed the point about valve clearance changing valve timing. That is the reason for the adjustment. Also the reason for the explanation about the mm and inch deal was because there are plenty of folks that have adjusted valves on these engines and used to thick of a feeler gauge and had the valves to loose (again with the valve timing).

Now for the injectors. After 2,500 hours or so they probably have carbon built up or worn tips, thus the suggestion of the rebuild or replacement. If you have more than one bad injector there is no sense in just moving them around. It doesn't fix anything nor can you identify the problem. A couple of bad injectors can cause a rich mixture and can make the engine burn oil as in blue smoke.