8.1 truck crankshaft work in 8.1 mercruiser?

[05 sangerdlx]

Have an 05 Sanger with the 8.1 H.O. Needs a new crank shaft. I know a lot of other parts interchange between it and the 8.1 truck engines, so, will the crankshaft? If not where is the cheapest and best place to buy one that will work?

 

[achris]

GM supply the long blocks to mercruiser. So a truck 8.1 engine of the same era /generation should be the same.

Chris. ...

 

[GA_Boater]

What happened to the crank? If the journals are worn or damaged, a machine shop can build up journals by welding and turn it down to spec. Depending how bad it is, that may be cheaper than buying a new or used crank.

 

[scoflaw]

I would think the HO version pushing over 400 HP would have a forged crank

 

[05 sangerdlx]

Rod bearing went out and chewed up the crank. I had it welded up and turned by a machine shop, put it all back together and it wouldn’t run. That was 4 years ago. Been to 7 shops since then and had the motor out twice since then. One shop said the crank was good but never pulled it out of the block, just pulled the oil pan to inspect it. Supposedly now the reluctor wheel on the back of the crank is damaged and has a couple cracked and broken teeth. How we didn’t notice that putting the engine back together I’m not sure. Since the only thing we did was pull the crank, have it fixed, and put it back in and the boat never ran since. It has to be the crank and the damaged reluctor wheel causing the boat not to run. Everything else checks out. Wiring harness, computer, crank and can sensors, it’s all been tested.

I had a post on here 3-4 years ago but couldn’t find it again.

 

[achris]

.... I had a post on here 3-4 years ago but couldn’t find it again.

https://forums.iboats.com/forum/eng...4560-8-1-mercruiser-keeps-frying-the-computer

 

[GA_Boater]

I kinda remember the frying computer thread. This one? https://forums.iboats.com/forum/engi...g-the-computer

It's so far back, surprised myself. :smile:

And slow! LOL

 

[Scott Danforth]

Same motor. Cast crank. Buy a new GMPP rorged crank

 

[achris]

Same motor. Cast crank. Buy a new GMPP rorged crank

rorged crank? What's one of those? :lol::lol::lol:

 

[Scott Danforth]

its the scooby doo endorsed crank..... the one with the fat fingers while typling on little keys on the phone.

 

[05 sangerdlx]

Yeah that’s the one! I didn’t look all that hard truth be told haha.

So are the cranks interchangeable between different years? Should I look up the crank by my vin and see if I can get a cross reference to a part number? Or just get a crank for an 05 8.1 truck engine?

 

[harleyman1975]

Zoinks!

 

[05 sangerdlx]

Yeah that’s the one! I didn’t look all that hard truth be told haha.

So are the cranks interchangeable between different years? Should I look up the crank by my vin and see if I can get a cross reference to a part number? Or just get a crank for an 05 8.1 truck engine?

Anyone? Need to order one ASAP and don’t want to have to pull the motor a 4th time if it’s wrong.

 

[scoflaw]

I believe the 8.1 came out in 2000. Check that part # and see if it's still the same in 05

 

[Fun Times]

To be safe you'll want to start off looking for an 2005 year model as looking over the early years there where a few superseded part numbers for the crankshaft plus there where differences in designs for the crankshaft sensor to match; That all finally leveled out right around 2006 I believe it was. I found your old serial number you posted back when (0W390234).

In the end of all the changes, Mercruiser ended up using merc part number 429-8M0084521 for the crankshaft for all the engine years but I'm sure there are other components you'd need to switch to make things all work together correctly depending on what year "one" would be replacing.

As examples for your situation; 'Take note of the early year from 2001 to about 2003ish regarding the old part numbers to the right of item number 3 and CAM sensors item number 12 (plus a few other parts listed as well of the following early years linked here)>, http://www.mercruiserparts.com/bam/s...31684/7460/110

Now here is your old original crankshaft part number (881654001) which again became 429-8M0084521 Item number 3, http://www.mercruiserparts.com/bam/s...1687/11740/110

Also if you read some of the "Notes" to the right of the part numbers, some of them mention the different block numbers...So you might want to find your block number as it may help too.

 

[05 sangerdlx]

Thank you Fun Times!

I know now when we put new cam and crank sensors on it we got the ones from the 8.1 truck engine, believe the same year. I assume they would work, especially if I got a crank from the truck engine.

So if they changed all the crankshaft part numbers to just one number, all the cranks should be the same then right? As far as the mercruiser cranks.
Called oreillys and they didn’t even offer a crankshaft for the 8.1 truck engine. I was just trying to compare part numbers.
Would a cast crank be okay in the boat if it’s an H.O.? Part numbers are the same between the H.O. and non. It’s a ski boat and doesn’t get beat on or top speed runs across the lake all the time.

 

[05 sangerdlx]

Bump ^
just want to make 100% sure before I order a truck crank. The people that sell the cranks won’t give me a for sure answer either.

 

[Fun Times]

At some point I was under the impression you were looking for a used crankshaft so I think looking for a year match for certain engines (especially early years) would be a little more important without truly knowing all the differences judging by the part numbers shown in the parts guide.

If you're going to buy a crankshaft from merc, then you should be okay with just the latest part number that comes up especially since your engine is an 05.

i would consider calling a GM dealer and see what their cost would be, check availability and try to get their part number and search it online and see what you come up with.

One other thought/suggestion to try and see if a company called http://www.raylarengineering.com/ happenes to have an newer takeout crankshaft that would work in your engine block numbers.

Raylar is an 8.1/496 expert company especially for high performance type stuff but they ought to be able to confirm or advise of a way to go about your needs if needed or desired on crankshaft issues and other internal issues too.

 

[chartersj]

What do you have for fuel pressure?

 

[05 sangerdlx]

Bumping up my old thread with some new questions.

Found the culprit. The reluctor wheel had a couple teeth that had a piece broken off. Guess I didn’t inspect it well enough on the install, and the machine shop I brought it too after it wouldn’t run didn’t catch it either. That was right after all the work was done and pulled the engine again to verify the crank was good.
Anyways, the engine runs now but when we plug the cam sensor in it runs like it’s out of time. The timing is on according to the shop. They say it runs ok until they plug the cam sensor in. What could cause this?