Yamaha 115 Blown Engine - Fix it or Forget it ???

[didg234]

Hi,

This is my first post here - so I apologize in advance if it is long. I am just trying to share as much information about our problem as possible -- with the hope that the readers can help us with our current situation.

We have a Scout 185 Sportfish with a 2000 Yamaha 115 2 stroke v4 - engine model C115TRY. My son and I were running it at top speed when it suddenly lost power and stalled out. When we restarted it we could hear something rattling around inside the engine so we turned it off and were towed back to port.

Rethinking the circumstances at the time we are not sure if the engine could have revved above 5500 RPM (redline for this engine) -- but that is certainly a possibility. If that did indeed happen we are assuming that this could have caused the breakdown.

I spoke with a local Yamaha service dealer and he indicated that internal noises are "not a good sign." This dealer has serviced other Yamaha engines that we have owned in the past and we have complete confidence in his ability. He then suggested that (worst case) it might need a new powerhead - but that can't be determined until the engine is dismantled to determine the actual cause of the problem.

The engine is in great condition and has been well cared for by us and the previous owner. However, we are faced with a real dilemma because the age of the engine and its actual value. We have to decide what is "reasonable" to spend on repairing this engine by weighing the cost of the repair versus the value of the engine due to its age.

He suggested we remove the spark plugs and check for any metal in the cyinders -- but none was found. We were able to start the engine and put it into gear - but we turned it off because of the internal rattling noises. The pistons, etc. seem to be OK because the engine does not run "unusually rough" like it would if there was a blown piston, etc.

We are afraid that if the dealer starts to dismantle the engine just to diagnose the problem, we are going to start down a "slippery slope" where we will end up spending a lot of money to fix this engine - and end up with spending more money to repair it than it is actually worth. We are mechanically inclined having completely rebuilt car engines and performed a lot of other repairs on cars, but we are not sure how to proceed here.

Having looked at some Yamaha engine schematics, and listening to the origin of the rattling noises while the engine is running - if I had to make an educated guess I would guess that there is a problem with one or more of the bearings around the crankshaft. We removed the carberator cover/air intake cover to listen more closely to the rattling noises - and the rattling sound seems to be coming from behind the carberators -- which is where the crackshaft and bearings are located.

The basic questions we have are:

1. Has anyone had experience with this kind of problem and can offer some suggestions of what the likely problem may be - and what is the best course of action to address it?

2. Is this something that can be fixed by dismantling the engine to identify what parts are defective -- and then rebuilding it to replace ONLY those parts?

3. If we attempt to dismantle and repair the engine --- are there other parts that we should plan on replacing while we are in there --- to avoid any future problems?

4. If we decide to repair the engine is it advisable to just repair/replace parts that are really defective - or is the dealer correct in advising to replace the entire powerhead?

5. Is there a reputable service facility where we could send the OUR powerhead to have it diagnosed and repaired or rebuilt for a lower cost than replacing it with a remanufactured powerhead through the dealer?

6. What sources do you recommend for getting discount Yamaha parts and/or quality Yamaha service --- at price savings that would justify repairing our engine - instead of replacing it?

Thank you for any and all assistance you can provide to help us with our perplexing dilemma ....

DIDG234

[jb123]

start with a compression test, that will tell you much

are you sure the noise is in the powerhead and not down low ?

if the rest of the motor is ok, T/T, lower unit i would drop a NEW powerhead on it and you will find the best prices here

[didg234]

thanks for responding to my posting. You indicated that I should consider a new powerhead for my 115 Yamaha and you provided a link to a site to find the best prices for a powerhead. However when I clicked on the link it took me to a site for marine electronics - and there was nothing related to the powerhead on that site. Is that the site you meant to reference or is there a different one?

Thanks ....

PS Unless I can find a powerhead for a reasonable price, I am still not sure if it makes sense to replace the powerhead - since the repairs might cost more than the engine is worth. Is there another option that costs significantly less - such as replacing just the defective parts?

[jb123]

noo i meant this site that you are on , here, posting... Boats.net

[99yam40]

you need to find out what the problem is before trying to find out how to fix

[didg234]

We realize that we have to diagnosis the engine to determine the actual problem before it can be fixed. However, our big dilemma is the potential cost to fix the problem versus the value of the engine (it's a 2000 model year).

Our concern is that once a mechanic dismantles it to see what is broken inside that is causing the "rattling noises" we may be quite deep into it financially and then we start sliding down a "slippery slope" where we ultimately end up with $4,000 - $5,000 invested in an engine that is not even worth that much.

Therefore, we are asking if anyone else has been faced with such a dilemma - and if so, what did they do about it.

Thanks for your input .....

[Once Bitten]

I can not comment on anything other than my own recent experience.

I recently blew my '95 Yamaha 90 and had a complete powerhead rebuild by a certified Yam mech/business owner. This included replacement crank and all piston and rods, all bearings, carb rebuilds, water pump replacement, two new batteries.
$2800 out the door. Factory power head price $3200 w/o install labor.

Hope this helps!

[Money Pit]

There is a place south of springfield Mo. That works on Yamaha motors and they rebuild power heands for minamial pricing compared to new motors. Look at there web site Hydro Tech is the name of the company and they did me a great job on reworking my injectors with a short turnaround time.