Omc 115 Turbojet stripped down and starting the rebuild

[Abomb27]

I have a 1996 Omc 115 turbojet, that I am going to rebuild. It is fully disassembled, and I just dropped it off to the machine shop. They are going to check the bore, and hot dip the block to clean it up. BUT they told me they cant bore it if it needs it. Hopefully it doesnt need it. I want to post my progress. First motor I am rebuilding, I find it interesting, hopefully I can het dome advice about things people have learned while doing theres. Im sure I will have questions along the way. And boobie if you read this I talked to you awhile ago about this motor missing a ring on 1 cylinder. There was almost no damage anywhere. The guy at the machine shop said all the walls looked good. One cylinder had some scratches that he said he couldnt totally get out with a hone. But not anything to worry about he said. I believe it wasnt put on, dont know what else to think. He said if a ring went the walls would be toast.

 

[racerone]

Re: Omc 115 Turbojet stripped down and starting the rebuild

Any damage to that piston ring groove ??--------Any pictures of that ring groove.----Fairly common for those to have a broken top ring that gets spit out the exhaust.---What does that marginal cylinder measure at now ?--Pictures of the score marks ?

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

I have to figure out how to post pics. There is some scratches on the side of that piston. Doesnt look that bad I dont think.

 

[racerone]

Re: Omc 115 Turbojet stripped down and starting the rebuild

I have seen many of these V-4 motors with broken rings.----Do my own boring and honing.----Nothing to it.------------Does not look bad is not the same as measuring the bore accurately.

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

I have a micrometer to measure the pistons, but could not find one to measure the inside of the cylinder wall. Thats y I dropped it off. I gave them the bore size, and they are going to check it. I agree I dont want to take any shortcuts.

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

I checked that piston again and it is scratched up on the one side and some damage in the same area on the ring groove. And it is the upper ring. My pics wont upload. I dont know why.

 

[racerone]

Re: Omc 115 Turbojet stripped down and starting the rebuild

You need to find / determine what went wrong here to make sure you do not have to do the job again soon.----Often these jet boats lead a tough on the throttle / off the throttle type life.----Post the measurements of the 4 pistons measured at the bottom of the piston skirt.--That ring was there and was spit out of the engine.

 

[boobie]

Re: Omc 115 Turbojet stripped down and starting the rebuild

Without seeing the piston, I'd say you're better of replacing it if you want to do it up right.

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

Got pics. Had to lower the image quality on my phone.

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

This boat was abused by previous owner and minimal care and maintenence was done to it. It had a lean condition, that I fixed last season. Ran well, im tebuilfing because I want it to be perfect, and have piece of mind.

 

[fishman204]

Re: Omc 115 Turbojet stripped down and starting the rebuild

Just the read I was looking for.I'm a little gunshy to do mine so I hope you keep posting.Hope all goes well

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

I love the boat and it ran well. Im just hoping I can get it perfect. The more I took it apart, the better I felt about being able to get it back together. Plus im in pretty deep now, so I guess no turning back. Lol.

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

I measured the pistons and here are the numbers in inches. Piston 1) 3.489, 3.493 2) 3.492, 3.488 3) 3.493, 3.487 4) 3.493, 3.488 I measured in two spots. My manual says 3.4930-3.4950 in. I am going to replace all the pistons. I figure it would be a good idea. Do those measurments tell me anything. Pistons a little worn out?

 

[racerone]

Re: Omc 115 Turbojet stripped down and starting the rebuild

Well the one that had the missing ring is scrap and the measurements on the others indicate they are worth about 50 cents / lb ---Scrap------Let me think how many times I have seen this damage.---------It needs boring / honing and 4 new O/S pistons fitted.

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

Any idea why the machine shop told me they couldnt bore thst kind of block. I guess I have to find a marine machine shop somewhere.

 

[boobie]

Re: Omc 115 Turbojet stripped down and starting the rebuild

If any of the other pistons look like the pic you posted, replace them all. How do the cylinders check out measurement wise ?? If they're okay you might get by with a hone job.

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

There at the machine shop. He said he will have it for me on monday. So I will post his findings.

 

[racerone]

Re: Omc 115 Turbojet stripped down and starting the rebuild

I guess they do not have the correct boring bar, nor the proper honing tools to do what is essentially a " blind hole "----Contact your local marina people to find out where they send theirs.-There are fewer and fewer shops that do this sort of work !

 

[Abomb27]

Re: Omc 115 Turbojet stripped down and starting the rebuild

Is it a good idea or bad idea to pay extra for the Wiseco forged pistons?

 

[boobie]

Re: Omc 115 Turbojet stripped down and starting the rebuild

I like the original BRP. JMHO but there are a lot of opinions out there about them.