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Cylinder bore question

Think about somthing.Your wanting to rebuild a power head for a 30year old motor.Do know if the starter works,fuel pump,alternator,ignition,tnt,does it jump gear at 4k does all this work at hi rpm?a 30year old motor is only worth so much running.
 
Rwbutler said:
Think about somthing.Your wanting to rebuild a power head for a 30year old motor.Do know if the starter works,fuel pump,alternator,ignition,tnt,does it jump gear at 4k does all this work at hi rpm?a 30year old motor is only worth so much running.
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Good points. I am going to wait until I speak to the seller before I do anything.
 
Some will argue-----I believe that a 1988 model V-4 properly inspected / rebuilt is a good motor for some folks.----If you have to run to a shop for every little issue.------The best solution would be a new motor with push button / computer assist.----Just open the wallet !
 
Racerone....I agree with you 100% on that one. Thankfully I am mechanically inclined and a consummate do-it-yourselfer. One mistake I made was assuming the powerhead was the only thing wrong with the motor based on what the seller told me and the unbelievably immaculate condition of the boat throughout. It was garaged it's entire life... the gel coat looks fantastic, has a perfect bimini top, high dollar cover that looks brand new, great tires, all original upholstery and carpet that looks near new. Inside are two later model high dollar fish finders, 24V 70lb trolling motor, 4 deep cycle batteries with 2 expensive on board chargers actuated via power cord from watertight gunwale connection. The entire rig was very well cared for and smacks of quality so I don't think the motor is complete trash. The seller is a fireman who seems honest as the day is long and I am sure he will level with me about the history once we talk.
 
Sounds like something I'd sure as he!! repair. Did you give Tim's Outboard a call?
 
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I did talk to Mike. Great guy! He has nothing now. He said he gets them but most of the time he sends them off to re builders because he does not get a lot of call for them. He told me to check back in a few weeks. I will do that if my block requires too much $ to repair.

One of the issues with sourcing a block is the cost of shipping. Before the online shopping explosion it was cheap for the little guy to ship. Now it's cheap for Amazon and other big guys and almost cost prohibitive for us with small accounts.
 
I has a chance to talk with the seller. He bought the boat from a friend who's father had passed away. He does not have any detail on the rebuild, doesn't know if it was done buy a pro or the guy that died, why it was rebuilt or even when it was done but he put about 60-70 hours on it since he has had it. The first sign of a problem was white smoke on startup. He thought it blew a head gasket which is understandable but both heads are flat and gaskets were fine.

More from the seller:

He used Pennzoil Marine oil

He never used the boat for long runs, boat launch to fishing area about 4-5 miles. Mostly used the trolling motor.

Never opened it up when cold

He did not change the impeller after failure but did buy a new one which he gave me NIB. After removing the lower unit I discovered the old one is in good shape

The motor did not do anything funny prior to failure that would indicate a lean condition. It did not backfire, hesitate under throttle opening or slow down as throttle was opened more.

I'm leaning towards VRO failure.

Other ideas?
 
Could be lack of oil too for sure. Not sure why the one cylinder looks good yet. Could be a VRO problem.....perhaps overlooked after the overhaul. VRO's are reliable but often fail from use of ethanol fuels. In newer replacement versions, the VRO ratios have been adjusted. If high quality synthetic oils are used they may disperse more oil than actually needed. I use Amsoil and with injected 2 strokes, like my old Merc 115, gets more than it needs. The injection line cracked off one night on the Merc while running after sunset.....didnt notice oil running out the bottom of the cowling. The motor seized up while freighting at WOT. Once it cooled down, it restarted. But after a second seize up, I noticed the leak. Trolled back 4 miles with the little Yamaha 9.9. Next day did compression test at a friends repair shop and replaced all brittle lines. 100 psi on all 4........ouch! Ran it all season, however, realizing I would have to rebuild it anyway. Now compression is at 90....all 4 cylinders. Pretty good testament for Amsoil........dont know of any other oil that could have helped this motor survive after 2 seize ups. Still runs sweet but not much power anymore.
 
Not a VRO or lube problem...if a oil problem the mixture would be lean (oil/fuel ratio) and the crowns would be cleaner and piston would be scuffed 360° not at 12 and 6 as the piston side thrust is at 3 and 12 and that where you would see first signs of oil failure damage. PM me if you need block.
 
faztbullet said:
Not a VRO or lube problem...if a oil problem the mixture would be lean (oil/fuel ratio) and the crowns would be cleaner and piston would be scuffed 360° not at 12 and 6 as the piston side thrust is at 3 and 12 and that where you would see first signs of oil failure damage. PM me if you need block.
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So if lack of lubrication is not the cause that leaves either a coolant problem or a lean air/fuel issue, correct?

The impeller looks good (pliable and intact) and water reflectors are in place correctly in the block. Any other things that can affect coolant flow?

I don't see a lean AF mixture as the plugs are dark brown, tops of pistons don't show it and seller said engine ran fine until next time he started it up and got white smoke. White smoke indicates water in combustion chamber. Could it be from a cracked block and if water did get in the combustion chamber would that cause piston scuffing and ring breakage? Heads are not warped.
 
STOP-----Draw a picture of a new piston and the top ring groove.-------Now put the ring in the groove.----------Measure the piston diameter near the piston rings.-----Now look at the amount of wear in the cylinder.------Note-----As the cylinder wears and as the piston and the ring wears things change.------The side clearance in the ring groove increases because of the ANGLE on the top ring.-----Thus the ring starts to hammer the piston groove at say 5500 RPM.
 
racerone said:
STOP-----Draw a picture of a new piston and the top ring groove.-------Now put the ring in the groove.----------Measure the piston diameter near the piston rings.-----Now look at the amount of wear in the cylinder.------Note-----As the cylinder wears and as the piston and the ring wears things change.------The side clearance in the ring groove increases because of the ANGLE on the top ring.-----Thus the ring starts to hammer the piston groove at say 5500 RPM.
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That makes perfect sense. But what about the scuffing. Is that from excessive clearance also?
 
Some 50 years ago my friend's dad asked me------Why should I use really good oil in my 1966 model 100 HP Johnson.----The motor just burns the oil.------That cemented the concept in my mind that folks do not know much about 2 strokes and lubrication on these wonderful 2 stroke engines.
 
My opinion:all this damage did not occurs at same time. It got a crapy rebuild it got rebuilt at all. And was not broke in properly.
 
racerone said:
Some 50 years ago my friend's dad asked me------Why should I use really good oil in my 1966 model 100 HP Johnson.----The motor just burns the oil.------That cemented the concept in my mind that folks do not know much about 2 strokes and lubrication on these wonderful 2 stroke engines.
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Racerone..... As mentioned previously the seller used Penzoil Marine. Do you think that contributed to the problem? What oil do you like?
 
This is an oh so common problem.----I think I could show you 15 to 20 blocks that have this issue.----As clearly stated / explained in post # 71.----Look into using WISECO pistons when you put it back together.
 
Racerone,

Thanks for addressing the ring breakage issue so common with these V4's. What do you think caused the piston seizing?

Phil
 
When disassembling the powerhead I notice the fuel line had been replaced and regular zip ties were used for hose clamps which I know is not advisable. The pulse line is also regular fuel line instead of the stiffer hose designed for pulse line. Could either one of those issues have caused a fuel delivery problem enough to create a lean condition to scuff the pistons?
 
Sorry-----The factory installed zip ties on many hoses for many years.----I rather use them than unsightly hose clamps.----Most steel hose gear clamps are overtightened !----My opinion only----People do not understand the concept of oil mixed with gasoline and what happens once the fuel goes through the carburetors.-------People invent new ways of destroying 2 stroke outboards every day it seems.------Motor ran too hot , that scores the pistons.
 
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Fuel line is fine, don't like that clear plastic, however. For reliability and longevity, I avoid polyurethane, tygon, vinyl, PVC.....why? Got rubber line on many 1950's outboards here.......still perfect. Keep away the ethanol, however....synthetics seem fine. Been using Amsoil in my 50's, 60's, 70's, 80's, 90's, equipment since it became available to me in 1976. Still wondering if anything I use is ever gonna wear out. Like Racer said, I'm still trying to figure a way to destroy these old vintage runners......yes I use em......they don't hang on the side of the shed. A sure way to wreck 'em is overheat 'em.
 
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Thanks timguy.....Aside from the obvious causes of overheating such as bad impeller, clogged intake, thermostat stuck closed (I know that almost never happens) excessively lean mixture or lack of lube what else can cause overheating in these motors? Are the older, larger 2 stroke motors ok with being run for extended periods at WOT or is it wise to avoid that?
 
Thanks Racerone...I'm still at a loss as to what could have caused the overheating. As mentioned before there are no indications of a lean mixuture. Can an impeller that looks to be in good condition not function correctly somehow?
 
No, it was not likely the culprit. I have seen weed collection on the intake area along with operation in a tilt position.....among other things, causing motor destruction. The impeller can get enough water to itself and prevent melting, but the water supply to the powerhead is inadequate.
 
timguy said:
No, it was not likely the culprit. I have seen weed collection on the intake area along with operation in a tilt position.....among other things, causing motor destruction. The impeller can get enough water to itself and prevent melting, but the water supply to the powerhead is inadequate.
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Hopefully one of those not so common scenarios occurred.
 
Can an impeller that looks to be in good condition not function correctly somehow?​
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Yes a weak impeller will cause overheat at idle..just cause it "pees" don't mean its cooling.This is probably the biggest culprit on 90° motor rectifier failures. Motor is "peeing" but block is not completely full. That's why the v-4s indicator tube should come off exhaust nipple, up and over top of head and down to discharge fitting. Now
just bore it next size( you can go in .010 increment's with WSM)..install new t-stats an relief poppets..new impeller..go thru carbs with new kits...If over .020 go up 1 jet size on mains..run good oil and fuel..will last another 20 +years easily if maintained
 
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