Problems with brand new Mercruiser 383 MPI

[Rogerdog23]

Quick update:

A new dealer spent the day looking at it and communicating with Mercruiser. Waiting to hear back from Mercruiser on Monday on whether they see anything wrong. They agreed it is sluggish and burning a lot of fuel but don’t see anything obvious. Found mIssing bolts on one of the motor mounts and are worried it is out of alignment and either took out the gimbal bearing or is putting pressure on the shaft to the outdrive. Will pull the outdrive Monday and see what they learn. They sound as if the alignment/ gimbal could be a big performance hit. Also found the engine is still running cool and could only get 151 on his ir temp gun and 158 on the gauge. Confirmed it is a 170 thermostat and can’t understand why it is running cold still.

more to come...place your bets.

 

[muc]

Pretty sure low temperature can only be thermostat or thermostat housing.
Alignment would have to be way off to get your performance. You should feel or hear something if it’s that bad.

Thanks for the update. Hopefully they find something.

 

[Rogerdog23]

They are worried the alignment is pretty far off. One of the holes where the missing bolt was supposed to go didn’t line up with the hole at all. He said when you lift the engine cover it’s pretty loud especially when in gear. Doesn’t sound bad from the helm but can hear something. We’ll see. Don’t know what to make of the temp. Bad thermostat that was just replaced? Too weird.


Mercruiser was thinking it could be something crazy like the ECU calibrated for the wrong engine or sometime the inboard version of the 383. With the report they should be able to tell on Monday.

Muc what would you be looking at next given the latest twist in this saga? Or are we at random guesses at this point? I think MC will ask for a compression and leak down test Monday as well. That was the plan if the recording and report looked normal.

 

[muc]

Did anybody find the missing bolts? If alignment is that far off, I would recommend. Gimbal bearing, ujoints and disassemble/inspect double bearing pack in the upper.

Test thermostat and if it tests good, replace thermostat housing.

Yes, they will be able to verify ECM calibration.

If the scan comes back perfect.

I would do compression test and then dynamic (running) compression test. I would only do leak down test if one of the compression test points to it.

Use the spark switch timing tool that MerCruiser wants their dealers to build and verify that the distributor is “clocked” perfectly.

Test and listen to the injectors closely to decide if they should be flow tested.

 

[Rogerdog23]

Missing bolt was nowhere to be found. They searched the bilge high and low but found nothing. The other one was backed all the way out but still in the mount at an angle. Not cool or safe for my family. Also sounds like serious damage may have been done. Now I don’t get to take the family out for Father’s Day as I don’t want to damage anything further if the alignment is off (50 hours on new engine though and if it’s out of alignment I’m sure the damage has already been done).

Appreciate the thoughts. Will give an update Monday assuming I have one. I keep thinking this will get fixed but we’ll see. Mercruiser has been incredibly supportive so far and now we’ll see if this continues or if they try to wash their hands of it.

 

[Rogerdog23]

muc How can the thermostat housing impact temp? Is this true on a closed cooling engine as well? Thanks.

 

[muc]

It’s the only thing I can think of that might cause it. Possible casting flaw? I don’t know, never had one run too cold that wasn’t a thermostat. Just a guess on my part. Don’t think raw vs fresh water would matter.

 

[Rogerdog23]

Got it thanks. Mercruiser continues to be supportive and is covering the new dealer to pull the outdrive and check alignment. Also covering getting the engine bolted down properly. They think damage to the coupler and gimbal bearing could result from misalignment but don’t think anything deeper in the outdrive could be impacted. Not sure what to think about that but doesn’t sound crazy?

Dealer pulled boat from water and will check alignment and gimbal / identify the noise that is coming from back there. Mercruiser wants to go down from 24” props (Bravo III) to 22.5” and see what happens.

 

[muc]

The prop change could be a good idea. I worked on a few boats that could be ordered with stock 496s or 496 HOs and the HOs always got smaller props to take advantage of the higher rev limit.

 

[Rogerdog23]

The max rpm on that engine is 5200 so not sure props will benefit me. Turned the exact same props on same outdrive at 5050 rpm with the old 350 mag. Not sure why the torque monster 383 with 50 more hp than the old 350 can only turn up 4900 on the same props. I’ll try anything though...who knows maybe they will help.

 

[gobuck]

I have the same motor in a 6000 lb Albemarle and have the same low temp problem and low top end speed. I switched from 22 pitch props to 20s. I still only see high 150s after running wide open. Dealer told me to replace the outdrive because it was geared wrong…..
Good luck.

 

[Rogerdog23]

Thanks Gobuck. How much speed and rpm did you gain or lose when you went down to the 20” props?

 

[Rogerdog23]

Update: Dealer pulled the outdrive today and heard a loud clunk when it was removed like there was a lot of pressure on it. Engine was WAY OUT of alignment they said. Gimbal looked questionable and they were planning on replacing. Weren’t sure on the coupler yet. U joints looked fine. Tech at dealer thinks the engine being that far out of alignment would definitely rob me of performance. Mercruiser disagrees and wants me to try the smaller props. I’m all for trying the smaller props but it will be another week or so before they can get them. I reread Muc’s post from yesterday and think I misinterpreted it yesterday.

Muc are you saying HO or higher torque engines actually benefit from smaller props? That seems counterintuitive to me but there is a reason I don’t do this for a living.

Any thoughts on performance hit from misaligned engine and questionable gimbal?

 

[muc]

The 496HO does, don’t know about your engine.
If they are willing to test different props for free, take them up on it. It is rarely a good idea to discount the advice from Mercury tech support. Stuff like this is all they do and they are usually very good at it.

Don’t know how much alignment is affecting your performance. Like I said before, If alignment is causing you to lose that much performance. I would be very worried about everything from the coupler to the double bearings in the drive. There are only two ways to inspect ujoints. Best is to disassemble and visually inspect. Second best is for a good tech to run the boat in the water under load while turning the steering from lock to lock while listening/feeling for vibration. If they didn’t do one of those two things, “looks good” means nothing. But if the gimbal bearing still feels perfect I wouldn’t be worried.

 

[nola mike]

If there was an alignment problem that was causing that degree of performance degradation, how has that motor not self destructed? Or had a *very* obvious noise at 4k+ rpm?

 

[Rogerdog23]

Thanks, Muc.

Here is the latest everyone...

Pulled the gimbal bearing and said it looked somewhat questionable so they replaced it. Not shot by any means but given all of the headaches they wanted to eliminate any doubt. Got engine aligned and bolted down properly.

They don’t know what to think about the coupler and said the only way to know for sure is to pull the engine and that ain’t happening this time of year.

They also drained the outdrive fluid that was just changed by the first dealer and said it was clear. Puzzled them as the quicksilver fluid is obviously blue / green. Did the first dealer put in the wrong stuff? Not happy about that.

Ran it on the hose today and said it sounds good and shifts good but they need to run on the water to know for sure. Waiting for smaller props to arrive tomorrow and will put them on and go for a water test. Personally I don’t like changing two variables at a time as you don’t know what to attribute the change to. It could be that the alignment was costing me RPM and going to smaller props will make it seem like a bigger benefit than they deserve. But like Muc says, trust the experts, do what they say, and see what happens.

Tech at Mercruiser finally chased down the temp and ECU calibration questions that were outstanding:
Cal—Was right on and the right one for this engine.
Temp—While it is only reading 160 they say that is normal for what they see in the Northwest and Northeast due to colder water temp. Say it isn’t impacting the fuel tables or costing me fuel efficiency / performance.

Okay, there’s a lot there to digest but thoughts welcome.

Muc, Mercruiser says they could see damage to the coupler and gimbal due to alignment but that’s about it. U joints are meant to flex and anything inside the outdrive (bearings included) are locked in place by a castle nut and can’t move due to pressure from bad alignment. So the damage would end at the gimbal or so they say. Thoughts on this? I don’t want to inherit problems that aren’t my fault. Other than being a bit slow at times Mercruiser has taken good care of me so far and seem to be honest and taking responsibility but possible damage is way above my pay grade so would value your thoughts on what they said. Would also love your thoughts on how I protect myself on the coupler? Don’t want issues there on my brand new engine but don’t know how to know if there is damage beyond pulling the engine. Any ideas on the clear outdrive lube and if that could have done damage? Maybe a knock off brand? Can’t imagine a Mercruiser dealer using anything but quicksilver.

Look forward to your thoughts...

 

[alldodge]

They also drained the outdrive fluid that was just changed by the first dealer and said it was clear. Puzzled them as the quicksilver fluid is obviously blue / green. Did the first dealer put in the wrong stuff? Not happy about that.

No issue with clear Merc lube and I would ask your dealer why they thought there may be an issue.

The clear stuff is the New Merc full synthetic racing gear lube

The old HP use to be 85W-90 NOW its labeled 90W
The new Syn gear lube is labeled 85W90
https://nuwavemarine.com/oem-mercur...hruRN0bXmZwD-9WvxNZY5PH02qrvWloRoCscgQAvD_BwE

I bought 5 gallons of each. Use HP in my Rinker and Syn in my Formula

 

[Rogerdog23]

Thanks a ton AllDodge. Mercruiser didn’t know what clear was either which is why I was worried. Have enough problems on this thing and didn’t need another. Thank you.

 

[Rogerdog23]

Also AllDodge. Why did you buy so much? How often do you change it?

 

[alldodge]

I only change once a season, just buying in bulk cost less. I have pump sprayers ready to go