mercedes 300d engines in my 26 ft Bertram

Hello everyone! has been a looong time since Ive posted but I believe it might spark some interest. After 4 years of trial and error, I believe that Ive finally got the build that Ive wanted for a long time. I have succesfully installed 2 mercedes 300 d turbo engines in my 26 ft twin bertram , I have paired them with 2 borg warner 2:1 marine transmissions. So far, so good. top speed , about 20mph. No manifolds or risers, all heat exchangers on tranny also. seems to run real well and sips fuel. Its "sweet spot is around 3200 rpm (all day long) My only issue is that they are running a bit cool, 150 degrees or so. I took out the thermostats but I dont want them, any thoughts?I think the engines would like a little more heat, but they run fine, no black or white smoke, except for a little white smoke at startup.Ill send pictures if anyones interested. Cheers!

 

No engine should run without a thermostat.
It's the wrong "fix" for a different problem.
Why did you take them out ?

3200RPM all day long you say.
How many pounds of boost at 3200 RPM.
What oil are you running?
Speed at 3200 RPM?

 

Guess what the thermostats do, thermo static, - stable temperature. The rate of coolant flow regulates overall temp, whether sealed, or sea, and the loss of restriction allows internal high velocities that all the components weren't designed for, from the pump to the hoses. High velocity coolant doesn't cool more efficiently either. Install thermostats rated to the engine's recommended operating temp., and your machinery will last longer. 3200 rpm seems a little high for continuous running, you may need slightly greater pitch props. Maybe an oil cooler too, for the turbos.

 

Without a thermostat there will be uneven temperatures in the engine. At worst it may crack the head.

 

I am running 15w30 as per the mercedes mechanic recommends. I don't know how many pounds of boost we have but we do have a new turbo boost line installed that runs from the intake manifold to the injection alt pump and that gives us much better performance. These are very high revving diesels that, with a tweeked injection pump can produce 200 horse each if done properly. They do it in Europe with them. Back to the cooling , what do you guys think of restrictor plates instead of thermostats? I removed them because it was running a little too warm before. Yes, I do have an heat exchanger for the oil cooler, raw water and antifreeze for the engine.Everything has gauges and warning buzzers also installed on the dash. Thanks for the tips, if you guys think I should go back to thermostats, I'm going to have to play around with them to get the desired temp. 180-200.

 

These temps stay pretty steady according to my gauges.

 

Please clarify:
1. Which engines exactly? There are several cars commonly referred to as "300D".
2. In the current installation the block is raw water or fresh water cooled?
3. What are the part numbers of the removed thermostats (should be stamped on).

As you can imagine Mercedes manufacturers several thermostats with different opening temperatures for different conditions.

 

The temperature may be steady, but it will not be even throughout the engine.

 

the engines are 1983 om617 engines from mercedes, they have turbos.The blocks are fresh water cooled , a pulley on the engine has a johnson raw water pump plumbed in for the heat exchangers. Salt water Never touches these blocks. I dont know what the thermostat part numbers were, been a long time since I pulled em.

 

You can choose between the thermostats with the following part numbers, opening at:
70°C/158°F A6172003015
75°C/167°F A1162000015 + Seal A6172030180
80°C/176°F A6172001815

Wich one exactly will keep your engine at the desired temperature range depends on the size of your heat exchanger and the composition of your antifreeze. The only thing you can do is try them.
It is highly recommended to install the thermostat, the engine will run better at the temperature it was designed for. Unless the block was hot dipped recently you should also descale it, and regularly change the antifreeze.

 

Maybe I missed it in the text but what speed are you getting at 3200 RPM?

The turbo version will not last nearly as long as the naturally aspirated one.
You've got to be using 15 - 20 psig to get 200HP.

Put the lowest temp thermostat(s) ( new ) in and see what kind of temps you get.

 

I am getting about 15 mph at 3200 , very heavy boat. Seems to be the sweet spot that these engines like, thats about 60 percent throttle, get the best fuel mileage about there.about 2 miles a gallon between the two engines. The cool thing about these Bertram convertible hulls is that they get up on plane almost instantly,(like at 5mph) there is no " getting out of the hole". We did have to spend some considerable time with the props to get em right.Thanks for all the help , you guys are the best, Ill try to figure out some pictures soon. I know some guys are really interested in this build, they do work but, let me tell you, to get everything right has been a pure labor of love, not too many people would do it..

 

Thanks for that Gary.

What are you in financially?

Are you going to install thermostats or are you done tinkering?

Ya, we really need some pictures. You can take them with your phone you know...

What props did you end up with?

 

Where are you find those engines dude ? Straight 5 turbo I'm not familiar with. I'm not familiar with MB engines at all. OM606 some guys used/use to 4x4 . I'm sceptic . Old design . Weak design .