410 Performance problem

You guys are worrying me. I am looking to move to a 410 with diesels. It seems like a lot of work and money to get the RPM's right. Is this a common problem with diesels, or only on some boats? Should I request full tanks of gas and water for the sea trial?
 
This is not an exclusive diesel issue by any means. It is not even an inboard issue. It is more noticeable to twin engine boats, as you have something to compare your performance to (the other engine). Once you have it set, as most people do directly from the factory, it is good until you (or Murphy) decide it's time to set your tuning awry by slamming one or more of your blades into some hard object. If you're particularly anal, as many of us are, you many find yourself pulling a prop or two a time or two until things are perfectly tuned and matched.

The key is to not exceed 80% of your WOT for more than a small percentage of your total operating time. During your WOT checks, you may find unusually low max RPM capability, which lowers your 80% cruise RPM, which may lower your expectations about performance and tweek your interest into making things better.

Yes, request full fuel and water. Don't listen to their excuses. Bring along 10 friends in case they won't add the gas.
 
Dani-Lu:

It's very important to turn (at least) the recommended RPMs for any motor so that you don't overload, and overheat, the internals....regardless of motor brand or fuel type. I am (now) of the opinion that a few extra R's at WOT, FULLY loaded, is the best way to prop my boat.

Dkruid 410's situation is a critical situation and mine is more just a matter of tweaking.

I'm only posting my experience's in this thread as a matter of comparison for Dkruid, and other 410 owners, with respect to the 410's props and, to some extent, the tachs, and relying on those tachs for an accurate measurement.

In my case, I purchased a second set of props (have/had spares for every boat I've ever owned) and that presented itself with the oppurtunity to 'dial-in' my WOT RPMs....that, in conjunction with replacing the tachs to digital for a very accurate reading (calibrated via optical tach).

The additional expenses involved with my prop tuning has been minimal. Having a set of spare props offers me peace of mind and the convienence of time. I'm not hauling the boat specifically to change props. I ran the entire last season with the props that are on right now and had not concern of causing any issues with the motors. However, since I will be performing my anual maintenance short haul in a few weeks, I felt it prudent to work the props at the same time in an effort to maximize my effeciency.

hope this helps.....
 
I was reading through the Operation & Maintenance manual for my engine and thought this was very interesting (quoted):

To establish proper cruise speed for any existing condition of a vessel, perform the following:

1) Run the vessel under way at maximum speed for about four minutes.
2)Take the tachometer reading. This is the maximum speed for the present conditions of the vessel.
3)Reduce the engine speed until the tachometer reading is 300 to 400 rpm less than the maximum tachometer reading observed in step 2. The engine is now operating at recommended cruising speed.

Operating at the recommended engine cruising speed will give maximum engine service life and most economical operation.

(end of quote).
 
My point was that Cat doesn't give any more precise requirement than "300 or 400 rpm less" which seems to be painting with a pretty broad brush. I thought 100 rpm is a big deal for a diesel engine.

I've always lived by the "max rpm with max load" rule like most of us who want our engines to last. Nowhere in the Cat manual does it go into detail about propping/rpm requirements. Granted their engines are used for many purposes other than marine, but you'd think they would cover this topic in the manual for marine engines.
 
I have attended 3 cat seminars, and in a published handout it states 85% of wot.Whatever it may be.

This is very specific.
 
I don't know when they changed their information, but the later Caterpillar engine manuals go into a lot of detail about loading, defining the classes of use and computing cruise rpms........unfortunately, the data is so complex that it almost takes an engineering degree to follow the logic and get the right answer
 
Yes and again yesterday. I had the fuel polished and the tanks cleaned because I was getting low fuel pressure on the starboard motor. We replaced the racors and fuel filters and now my fuel pressure is above 65 on both motors. I still have the same issue I started with though, only 2650 RPM on the motors. They are now going to pull off and clean the aftercoolers and turbos. I will keep you informed as to what they find.
 
Just curious (Couldn't sift though all the pages). Did you ever get your bottom thoroughly power washed?

If you did not, that IS your problem. I have fixed this same problem on both my 330 Dancer, and 450EB by simply power washing the bottom. Adds 4-5 knots every time. I am in Fresh Water, and do use my boat. The slime will definitely get you in just 6 mo.

If you have not hauled and sprayed your bottom, you have spent a ton of money for nothing. If you have, I had a friend with problem like this, and it turned out to be a small leak in his trim tabs. The tabs worked, but did not stay down under load.

- Tim
2003 450EB
 
FYI trim tabs are not to be used in the attempt to achieve maximum or rated rpms. as I'm told by the surveyors and cat mechanics.
 
I have the bottom cleaned every three weeks but no I have not had it hauled out and inspected. My diver says it is in good shape. The previous owner had the bottom redone in May of 07'. I have checked the trim tabs and they are good. Aftercoolers are coming off tomorrow to be cleaned. We'll see.
 
Are you aware that the 3116 and 3126TA's have a known problem of fouling the aftercoolers due to the use of multi-viscosity engine oils that are not synthetic like Rotella T and Delo 400 15W40? Such oils have additive packages containing viscosity enhancers that tend to break down and leave deposits in the aftercoolers.

The remedy is to clean the aftercoolers, as you are doing, and the prevention is to use Caterpillar SAEO, Special Application Engine Oil, Cat part no. 170-5261, or to use single viscosity Rotella T or Delo 400 in SAE 30 or 40 depending upon your ambient temperatures. The Cat SAEO is synthetic and the others do not contain viscosity enhancers.
 
Yes. The CAT mechanic is thinking the previous owners may have used the wrong type of oil and brought that to my attention about using the CAT oil. Thanks
 
DKruid, I was just wondering how things worked out with the aftercoolers and if you ever were able to get the problems repaired? Inquiring minds want to know....thanks
 
I had the aftercoolers put back on 6-6. I sea trialed the boat and there was still no difference. Speed was still 26.5 MPH and RPM 2600. Frustrated, I had the boat pulled out of the water yesterday and the tech says my bottom is the cause of the problem. I am having the bottom redone as we speak and they will be putting it back in the water on Tuesday for another sea trial. I have the boat bottom cleaned every three weeks and have never gotten the WOT RPM that it should. But the CAT tech and bottom guy says that this should be the last piece of the puzzle and that everything I have done should get me to the 30-31 MPH and WOT that I have been desperatley looking for. Fuel pressure is great, 65 psi, props changed to 21.75X 21.75 very light cup, aftercoolers and turbos cleaned, and bottom paint redone. CAT says all specs on motor are great with boost pressure and gauged for blow by, fuel pressure has been tested and is also great. My fingers are crossed do to 4 months of pulling my friggin hair out! I will let you know on Tuesday night. We leave on Friday from Ponce INlet to go to the Bahammas for 2 weeks and I hope we have got everything right. If anybody has any other input it would be appreciated.
 
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