PLEASE HELP!!671 tib problem

[35viking]

Yesterday we took the 41 viking out for the first time this year since last fall. When we started it up to warm it up .The port motor it did not sound right and it was running really rough .We have always had a problem with this motor it has one cylinder that has low PSI and it always has white smoke at start up until it warms up.It has only a 100 hours on it after rebuild. we idled at the dock for a little bit until it warmed up and then started going down the river and there was a fuel/oil coming out the exhaust we determined it was unburned fuel coming out. There was tons of white smoke like a constant white cloud coming out of that exhaust even in just idle giung diwb the river. Once we put it up on plane and throttled up it all went away and was perfectly fine.Temp oil and rpms were fine. Is this something to worry about? Will it happen agian? How do we fix it? Is it a cylinder or injector ? it was the first time since last year we ran the boat so could it be just because of not being run. Thank you in advance.

[seapower]

Alway's had a problem even after rebuild? One cylinder has low PSI, with only 100 hour's since rebuild? Without being there I think I would crank her up, pull the valve cover and deaden the injectors. Pay close attention, if the rpm doesn't drop, investigate that cylinder. With the symptom's you are reporting it doesn't sound like a fuel problem. It sound's like it's getting the fuel, but doesn't have the compression to burn it. You need to find out if the lack of compression is from the ring's or the valve train, this has the potential of saving you alot of work. It's very common for valves to stick, this will only lead to the building up of carbon under the seat. All head shop's are not created equal either, if the valves were not ground correctly, same deal. Weak cylinder's don't generally fix themselve's. If you knew after only 100 hour's that you had a weak cylinder, I'm pretty sure I know what I'd be doing. Break out the wrench's Capt. If it's not too late already, if you don't get rid of that raw fuel problem you will be looking at another failure. Frank,SeaPower

[EnginesInc]

These symptoms sound like a cold stuck ring. DDC uses a fairly low tension barrel faced fire ring on the 71 TI cylinder kit, which sometimes does not seat at initial startup until enough heat and combustion pressure are present. Was the compression taken at operating temperature? Does the smoke return after several minutes of idling? This is fairly easy to diagnose as long as access to the outboard side of the engine is available. Assuming that the compression is already known to be low, and you have access, a knowledgeable Detroit mechanic can check the rings for tension when cold by gaining access through the air box. He may determine that a ring is broken. I doubt it will turn out to be a valve based on the reported symptoms.
If it is a stuck ring, repair will involve removing the piston to change the ring.

Larry Pecan
Engines, Inc.
Pleasantville, NJ
609-485-0101

[seapower]

I don't know about the rest of the world, I can only answer for myself. A hundred hour's is a hundred hour's. If I rebuilt an engine (the way it should be rebuilt) and it was missing with a low compression reading on 1 cylinder, you can bet I'd be finding out why and doing what it took to make it right. Engines are meant to be ballanced while running, that means equal compression that leads to equal firing at all loads. Compression, timing and fuel is what it boils down to, no matter the color of the engine. You need to run the engine after rebuild to seat the rings (break in), after the rings have had time to seat, compression should be within spec's, Period!!! If not you got a problem, do the troubleshooting and fix it,Period.
I had reservation's about commenting on this post, because of the obvious potential to get in a "urinating contest" with an expert. Any response by me is to help the person that started the post, that's it that's all. As stated in my first post on here, this ain't about money. I'm selling nothing, that's why you don't see my name, address and telephone number at the end of any replie's. Frank

[JD5652]

35Viking-

You've gotten some sage advice from two people that know what they're talking about. One thing is for sure....DO NOT WAIT to address this problem..... a picture speaks a 1000 words....that head had less than 400 hours....#6 cylinder compression was 378 psi.....

[seapower]

Thank's for the vote of confidence. In this business it seem's you have to give folk's info that they really don't want to hear almost every day. Iqnoring or questioning the problem very seldom makes it go away.
There are a number of thing's that'll cause excessive "white" smoke at start up. But with a known low compression value on 1 out of 6 cylinder's, it's time to start digging. I wouldn't consider running it until I knew what was up. Whether it be a ring (I've seen several cases of a mechanic putting a set of ring's upside down, just for example), valve train,piston/cylinder problem, it needs to be nailed down. I've seen crankshaft's crack and split from this problem. Seem's to me that time is on his side, he should take advantage of it.Frank

[35viking]

thank you for all the replies. We ran the boat again today and it was fine just some smoke at start up but once it warmed up it went away. No smoke and fuel at all. We also checked the rpms directly from the motor and they were the same as the other. Should we worry about it or forget it and leave it or should we break out the wrenches and start breaking down

[canyongear]

Borescope the low cylinder? checkie the cylinder wall at least since it is a compression issue at least eliminate a busted or f'd ring install.

[JD5652]

thank you for all the replies. We ran the boat again today and it was fine just some smoke at start up but once it warmed up it went away. No smoke and fuel at all. We also checked the rpms directly from the motor and they were the same as the other. Should we worry about it or forget it and leave it or should we break out the wrenches and start breaking down

Did the compression magically increase? The same RPMs on each motor doesn't prove anything other than you had the engine properly synchronized.

You've got something going on in that engine and you can either address it now or wait until the middle of prime fishing season....your call.....

[canyongear]

Did the compression magically increase? The same RPMs on each motor doesn't prove anything other than you had the engine properly synchronized.

You've got something going on in that engine and you can either address it now or wait until the middle of prime fishing season....your call.....

JD's right..and the bill will just go higher as things get worse..if there is a true cylinder problem..any recourse you had with the rebuilder will be out the window by that time since this is now public knowledge in www. domain that you knew there was an issue and decided not to address it.