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JOHN W MAYO posted 03-29-2004 11:09 PM ET (US)   Profile for JOHN W MAYO   Send Email to JOHN W MAYO  
Today I took the boat out after I de-carbed the engine using tectron. After researching on this site many post about using the product. I added 16 oz to 6 gal fuel/oil mix. I let it idle in water for 1.5 gallons of fuel burn, then burned the rest of the fuel at various speeds and cruse. I did have a much better rpm of 5200, before I only got 4800 rpm in testing the max power.
It ran a total of 13.1 nm. Smoth running at cruse of 23-26 mph and 4000 rpm. Then the problem started. I decide to see how the performance was out of the hole to get on plane quickly, and was going to change props afterwards but....bad news, noise, sudden stop of eng. It did recrank and operate but would not get on plane, 13mph max. I took the cowling off, plugs etc., found the eng block cracked 3 inchs right where the front of the eng attaches to the plates that hole the plugs, this is located by # 3 cylinder. An inspection of # 3 shows a fowled plug, probably aluminum, and probably aluminum in the cylinder plug hole. It is a unusal area to crack, right at the lip of attachment area. Could the use of the tectron have possible caused this? It seemed like it worked but I not to happy with the end of the day results. It may not be at all the cause, and is probably not. Just trying to figure what went wrong and if I can repair it.
I do all my own engine / boat work.
compression check next step.
Any suggestions to keep her running?
Eng 1976 merc 1500 150 hp , original engine installed on my 1976 Revenge 19.
Sal DiMercurio posted 03-30-2004 09:59 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
It's obvious why the engine blew.
You don't say what engine it is, but 4800 rpms is to low for any outboard.
You over propped the engine & she finally gave up.
While decarbing, you shouldn't be running her at wot either.
In order for a de-carb solution to work correctly, it must soak the hard carbon to soften & liqify it @ low rpms, then let it sit.
At wot the solution is getting burned off before it can work.
kglinz posted 03-30-2004 11:54 AM ET (US)     Profile for kglinz  Send Email to kglinz     
Your engine did a great job. 28 years is more than anyone could expect. To find out what happened you will probably need to tear it down. Sometime if an engine, with ports in the cylinder walls, has heavy carbon and is decarboned a piece of carbon gets caught in the port when the piston moves past the port. Now is a good time to buy a carb or EFI engine before they go away, or change to a Low Emission engine.
Bigshot posted 03-30-2004 12:51 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
If memeory serves me have had low compression or something with this engine for a while. To stuff a piston it takes a while. A good season of a clogged carb or something that caused it to only run 4800 is your problem. She was getting hot and finally when it wore down enough to break a ring is when you tore it up. The carbon could also have been holding the ring in place and the cleaning released it right into your cylinder. 28 years is more than anyone can expect and personally I would go with a new 140 suzuki/johnson 4 stroke which is plenty on that hull($7k).
Bigshot posted 03-30-2004 12:53 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Oh.....NO it was not the Techron's fault nor how you used was just time.
hooter posted 03-30-2004 02:47 PM ET (US)     Profile for hooter    
Solvin' your problem like a good engineer, say like ole Tom Clark: as you know, one human year equals seven doggy years. That '76 been runnin' pretty doggy, you say now, for almost 30 years. So usin' the aforementioned formula, that engine is approximately 200 years old. Techron acts somethin' like Viagra for boat motors. Some say that the Techron didn't kill it? What d'you think would happen to a 200 year old man if he took a dose of Viagra? Die with a smile on his face, is what. Check to see if that old engine wasn't smilin' when it died; There will be your answer, and you don't need no chain saw to figure it out:-!
dfmcintyre posted 03-30-2004 06:13 PM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
And following Hooters line of thought.....according to at least one MD I know, the use of Viagra might be countraindicated for, ahem.... patients with preexisting heart problems.

And at that age, in engine years, that 'ol guy just might have had a pre-existing condition!


JOHN W MAYO posted 03-31-2004 01:52 AM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
Boy, what good comments......I think pretty much you are all right in your thoughts on this one.
Sal, I did state what the engine was, it was in the last sentence of my post. I had replaced the lower unit with another one and was trying the prop/lower unit to see how it did. The engine actually gave me about 400 more rpm...not sure if it was the prop or the tectron, the latter I think. The prop that was originally on there was a P17, this is what I was going to put back on.....but did not as I could not get the other one off. (Stuck on)also, do they make one much lower than 17? I could not read the number on the prop that was on when the engine went, but suspect about a P23. So you may be right. But the 5200 rpm was the most I ever saw after the tectron, lower unit, and different prop. A big surprise.
I did burn 1.5 gal of gas/techtron/oil at idle and let it sit overnight.
Bigshot, Yes you are correct, you have a good memory! I had previous problems with the Mercury 1500. About a year or two ago the #3 cylinder had only 15 psi, but I change the plugs and kept running it, it improved aparently greatly(after sitting for 3 year when I purchased it and I ran it for another year or two. Surpisely I got it running pretty good but the max rpm was about 4800 / speed 36 mph on the 19 Revenge so I could not bear to trash it as good as it ran. (#3 is the aprarently the one that blew)
hooter, I was told by a friend that goes with me that "run it easy and it will probably last, it old so it probably can't take running fast". Kinda like the 200 yr old man and Viagra. Yes, it did have a pre-exsisting condition .At least it had a good run reaching that peak 5200,It had to be the Viagra. I plan to tear her down and see what it looks like and ???repair??? if possible.
Thanks to all for yor input.
Jarhead posted 03-31-2004 07:27 AM ET (US)     Profile for Jarhead  Send Email to Jarhead     
"and repair if possible"...

Gotta admire your tenacity John. ;)

Sal DiMercurio posted 03-31-2004 11:11 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
John, those props go down to a 13p.
I doubt very much if the prop that was on when she blew was a 23p, because you gained 400 rpms when you changed the lower unit which means that prop has 2" less pitch.
I would think it was a 15p & the previous one is a 17p.
If the new lower unit had a 23p going from a 17p, you would have lost 1,200 rpms & ran at 3,600 instead of 4800, but instead you gained 400 rpms so it means this prop is 2" less pitch.
Sorry, I didn't read the last sentence, as I thought you were just explaining that you did your own work, sorry about that.
JOHN W MAYO posted 03-31-2004 11:54 AM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
kglinz, the tanacity comes from liking the old girl and not wanting to buy that new engine just yet.Thanks.
Sal, no problem, I always read your input and advise as I know it is worthwhile and I learn from your comments. I tend to agree with your statement about the prop pitch and how it increased the rpm, but, I can look at the prop on the engine and it apears the same, if not a little more pitch than the one I was going to put back on there. I know that a higher # pitch normally reduces the rpm. if I can ever get the prop off and can find a number I will let you know. I had done a search and found where someone in the past had de-carbed and gained about 400rpm, so that was kinda what I thought happened to mine. The lower unit I put on there came off a smaller engine, I think I took it off a mercury 1000. Possibly a gear difference? I Don't know. I would have not even considered changing it except I had a new prop and the one on the lower unit I installed looked like it had been hit by a truck.
All input appreciated.

JOHN W MAYO posted 03-31-2004 12:02 PM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
I may have answered my own question. That prop being distorted some from damage may have had less bite, and therefore more RPM, I am not sure if the damage was enought to do that thought.
JOHN W MAYO posted 03-31-2004 10:29 PM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
I just did a compression check of the engine and was really surprised how good the good was / and how bad the bad was.
4 cylinders had a compression of 120-122 (2-3-6)
2 cylinders had a compression of 0-5 (1&5)
I put some grease over the crack in the block and suspected it to be blow out when I cranked it over, but surprised, it did not appear to be leaking.
vdbgroup posted 04-04-2004 11:33 PM ET (US)     Profile for vdbgroup  Send Email to vdbgroup     
16 ounces to 6 gallons of fuel? Huh? Check the label on the Yamaha ring free - TEchron product. More like 16 ounces to 64 gallons. If I remember right.

Sal DiMercurio posted 04-05-2004 12:13 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
The shock treatment is a much stronger mix.
I believe the 16 oz to 64 gallons is the maintenance mix.
Bigshot posted 04-06-2004 03:00 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
John.....time to put the ole girl down. Cracks in blocks, etc are not ood subjects to rebuild. Parts are gonna run well over a grand and special tools and manuals are needed. If you do decide to resurrect the beast, buy a rebuilt powerhead and swap them. Make sure yours comes off first.
JOHN W MAYO posted 04-06-2004 06:28 PM ET (US)     Profile for JOHN W MAYO  Send Email to JOHN W MAYO     
vdbgroup, I use the amount that I had found on a search of this site. You may be correct, but, I read sevearl post on the amunt I used...I would not intentialy use an excess amout.Thanks for the info.
Bigshot, I think you may be right. After checking on cost, etc., it may not be worth it. I just checked with an old timer, marine shop, who works on old Mercury engines, and he wanted no part in rebuilding the old 1500. He said it is to much of a headache trying the reassemble the pistons etc as it as to be done all at one time.
The cost of a Kit to do it is $ 890.00, for parts , plus extras,special tools, manual, machine work, etc. added to that. It looks like it could easly be 2k or more. I do have an old 1400 engine that I bought for parts that I could maybe use. If I rebuild it, I will do it myself just as a project to get me by for a little while. When I bought the 1400, I was told it did not work. After taking it down to the pistons, the main thing I could find was the drive shaft, lower unit, was rung into. I never expected to use the block so I took it apart just for educational purposes to see how it work.......If I had not done that I may could have use the power head as it was. It might have worked, maybe not.
I think you are right Bigshot, time to put her down. I jsut can't force myself yet to do. I was hopping to take her to
Bigshot posted 04-07-2004 10:33 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Bring her down....good deals on engines here. While we drink beer in stuart, you can have it mounted:)

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