Gearbox Problems :-(

Hi, I am wondering if anyone can help? I am having problems with the gearbox on my ketch. Firstly the name of the engine/gbox is a Lomatec its 36 hp.
The engine appears to run okay although when selecting either forward or reverse I get no power to the prop. An example is the motor is running at 2500 rpm and only doing 2 knots. The prop is clean with no growth on it. It appears to select the forward and reverse gears with no problem. The engine has only done 50 hrs and was installed in 2009. Any help or suggestions would be great.

Cheers Jerome

 

Sorry to hear about your Lomatec, but these seem to be Chinese knockoff or a marination of a Nissan with less than standard parts installed. I heard very little good about them. There seems to be several importers around the world for them and good things about attempts at good customer service have been reported.

Contact:

Mr. Wang Jianyou
Jiangyan City Loling Machinery Factory
Taiyu Development Area, Jiangya City Jiangsu P,R. China
0086-523-826-1662
jywtl@pub.tz.jsinfo.net

This aside, the issue sounds like it could one of several, mostly simple things to check out. Have you had your local diesel mechanic take a quick glance at her? He will likely find out what it is within 5 to 10 minutes.

 

Thanks for your input PAR. I like you have read a little about this particular motor, not all bad but they are as rare as hens teeth. Unfortunately my boat is some distance away from a mechanic of any sort. Keep thinking it's got to be in the gearbox.
Thanks for the info and will I make some more inquiries.

Cheers

Jerome

 

No power..but it still makes 2 knots? So some power is getting through.

-prop spinning on shaft.
-internal gear spinning on shaft.
-clutch slip or linkage adjust.

 

As West said;-

Some of the keyways can be a little too soft - and shear if the prop is unbalanced or slack.

If the boat is out of the water, pull the prop and check that keyway first - usually easier to get to. Then the one at the gbox end of the shaft - a good trick when installing is to center punch the coupling to leave a dot and the same on the shaft close to the coupler and lined up with the first - if the shaft works its way out the dots get further apart and if the keyway goes then they stop lining up. You can do a similar diagnostic with a sharpie (marker) by running the motor on the dock with the boat well fendered and tied.

Have you checked the gearbox oil - don't know that particular box but many use the oil to actuate gear selection - low or wrong oil will cause that symptom - some smaller gearboxes don't have a dipstick and a socket or wrench is required to check level (AKA it doesn't get checked 'till theres a problem).
The oil should be clean after only 50 hours and no metal particles.

 

What type of prop is it. I had a folding prop that used to stick sometimes and do the same thing. The boat would just move very slowly. If you have a folding prop its a possibility. Also you say it is selecting gear ok. But are you talking about movement of the controls or have you physically got down and checked the lever travel at the gearbox.

 

Thank you both WestVanHan and AndySGrey for your assistance.
It appears to me that the shaft is slipping or that gearbox is. My thought is if the keyway at the prop is sheard then the prop wouldn't be able to push the boat? however it's possible that it could be slipping at the coupling. I suppose worst case scenario would be the gearbox is the culprit. The boat at present is on a mooring some 45 n/miles away from a slip and mechanic. The hints that you have offered are helpful and may help me eliminate some of the possible reasons for the problem.
Once again thanks for you assistance

Cheers Jerome

 

Hi Whitepointer23.
I have been and checked physically that the leaver is pushing the gear selector into the forward and reverse gears. The prop is a fixed 3 bladed prop.
Thanks for you contribution.

Cheers Jerome

 

no worries.

 

Jerome can you swim under the boat and tie a block of wood onto the prop to lock it. If you can do that and put a long pair of stilsons on the shaft flange at the box. If you can turn the shaft you will know if its a key and which end it is. Thats what I would do.

 

Hi Brendan,
I will give it a go next time I go to the boat. She's some distance away (90 minutes drive each way) so when I go back down to her I will be armed with alot of info.

Thanks again
Jerome

 

The key can shear and leave enough remaining to bind up, as the chunks bounce over the key rubble. Of course this doesn't do good things for the shaft, but if taken care of quickly, often you can file things up and get back in service.

 

Brendan has the best idea but you can maybe do a test without any diving.

Get some vise grips or a bar,have it in gear,and see if you can get the shaft to spin inside the transmission.

Let us know...

 

Hi WestVanHan,
Thanks for that, I will be heading down to her this Friday and will utilize all the info everyone has kindly offered.

Cheers
Jerome

 

My very initial thought was that the prop is fouled by rope or netting,but you state it's clean.

Other thing to do is take a strong magnet,and run it along the bottom of the transmission so as to drag any metal shavings (if there are any) towards the drain. Go over it a few times.
Drain the oil and see-shavings = key way or gears stripped.
No shavings and dark=clutch.