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Joined: 6/18/13
Posts: 81
Loss of power under load

I’ll try this again.  My M35 1995 has lost power under load.  Had 3000 rpm at full throttle.  Now about 2300 rpm.  In neutral it revs to the normal 3000 rpm.  A diver cleaned my prop.  My fuel system was bled of any air.  I’ve seen in posts others experienced this problem. How has it been resolved by the past victims.  If it revs fully in neutral and not in gear does this suggest any thing specific.  Someone suggested an injector problem but wouldn’t this. Affect thRevving in neutral as well.   Any suggestions will be much appreciated.  Thanks, Bill

Bill and Carla Reitz C-36 MK-2 1995 W/K Kind of Blue #1427 Sausalito Ca

Siler Starum's picture
Siler Starum
Joined: 4/20/18
Posts: 63

We faced this issue unfortunately also yesterday, in neutral all OK and when clutched in the revs are dropping drasticly and the engine is almost stopping.
Starting normal, no smoke etc.
First thought was something in the propeller, however this appeared not the case so we managed to arrange a tow back home. 
Filters are OK and no condens/water.
A challenge today to continue figuring out the problem - my thoughts now are heading towards failing of the electrical diesel pump.
Something different then enjoying sailing without worries during holidays... anyhow having this kind of issues are not improving thrust in the M35B.

Siler Starum's picture
Siler Starum
Joined: 4/20/18
Posts: 63

update from my side power-loss:

I checked the FO-lift pump with external 12VDC supply and the pump was nicely "ticking" and working. 

When the contact swich is in "on" position the lift pump should work already - which was not always the case and therefore I digged into the cabling again. 

I figured out that the 12VDC feed to the FO-Lift pump is in series with the LO-pressure switch, the bad/broken contact on the LO-pressure switch stopped the FO-lift feedpump causing not having sufficient fuel-supply with the power loss as result when more fuel was required under load.

So in our situation the problem is caused by a bad/broken contact on the LO-pressure switch.

Temporary by-passed the LO-pressure sensor whilst sourcing here for a new sensor which fits - so that at least we can continue our vacation. If the case will be that the engine will be destroyed due to low oil pressure there is at least a good reason to put a good engine like Yanmar in with the European parts center nearby and service points on almost every corner of the street here in Europe. (apololgies but the onliest issues we have with our Catalina 36MKII were till now mainly related to the Universal engine)
Presume anyhow to get an "original" one from Universal will be extremely expensive (due to all the new trade-sanctions introduced by the present USA big boss as for sure the part is produced in China) and will have a long lead time.

Positive thing is that at least now I know which one of the many different electrical diagrams I have is most likely the correct one, and can use this to dig furhter in the other electrical engine issue which has been put on the forum also many times already: the proper operation of the instrument panel (no revs, , hour counter working when it likes, far too high voltage indication), alarm buzzer not working (sometimes it does). During the winter season I measured all wiring through already, where no issues in cabling was found.


KevinLenard's picture
Joined: 1/28/15
Posts: 163

Just a heads up, on our '91 we were heating up to 190 degrees on the gauge at 2,000 RPM (I like to keep it at 180, but against a head wind/current I let it go to 190) and we get a reliable 7 MPH out of her.  Any higher RPM and the swim platform and exhaust start going under with no real improvement in speed and overheating.  (I put in a new thermostat recently.)

Turns out we had a broken engine mount on the forward starboard side that might have been broken for ages and this had led to the stern starboard engine mount nut coming loose (or the loose stern mounting nut led to the forward mount breaking).  Once I had the bracket welded and replaced I did the transmission flange to drive flange levelling exercise and levelled the engine on the starboard side.  I am fearful that I did some damage running her for many hours while off level, but the cutlass bearing seems OK, as do all the other fittings.  (She's up on the hard now due to our recent grounding incident...)

Once I did this she runs up to temperature at only 1,950 RPM and we still get the steady 7 MPH.  I'm not certain that checking the level of the engine did this trick, but it might be worth a try for anyone seeing a need to run at 3,000 RPM and/or running hot.

LeslieTroyer's picture
Joined: 3/13/16
Posts: 512
A rough alignment can be done on the hard, but needs to be repeated in the water. Check that your stuffing box isn’t too tight (hot while running).
Chachere's picture
Joined: 10/27/10
Posts: 679

One thing I would suggest you check -- particularly as you are on the hard, where you can do it without causing a flood! -- is the condition of the shaft tube (a.k.a. "shaft log").  If (as I gather from your description) the engine RPM loss was due to severe mis-alignment, its possible that the prop shaft was rubbing on the shaft tube.

If I'm remembering correctly, there is only maybe 1/8" (3mm) or so of clearance between the shaft and the  tube, and a bad misalignment can grind part of the tube away (necessitating a rather nasty repair job, as documented by yours truly and other members here: www.catalina36.org/forum/technical-discussion/shaft-tube-removal  ). 


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