Seller blames me for loss of compression

[volundur]

Hi there!
I'm having a bit of a trouble with a 1979 CHRYSLER 700 SKIER outboard I bought from a guy. It is obviously used, but is in a quite nice cosmetic condition and had just some minor things to fix when I bought it (got it relatively cheap).

The problem is that I have not gotten it to run properly, it idles very good but as soon as I try to take off and give it gas it just bogs down or stumbles and quits. - I can actually run it with the throttle wide open but the speed of my 15 feet speedboat is not much to talk about. Id go fasted with the old 6hp.

Well, I contacted the seller and asked for advice, and to make a long story short we found out that cylinder number 1 (the top one) has no compression at all! the other two are 170psi.
- The seller is now blaming me for having used a wrong fuel mix which may have led to a broken piston or cylender wall. I carefully measured the oil and gas and ran the motor (mostly on idle and this bogged down speed I wrote about). I used 1:50 ratio of fuel and outboard 2stroke oil. - but the seller states that he always used 1:30

My question is: - is it possible that the seller is right about the oil ratio? I did my research before mixing and running the motor on the gas and it all pointed towards 1:50.

I'm going to pull the head off in the next couple of days to see if there is a proken piston. All ideas are welcome

p.s. pardon my english, I hope I make myself clear enough

 

[bentle]

Re: Seller blames me for loss of compression

Im not to familiar with your motor but I believe the mix is 50:1 and not 30:1. To much oil or to rich will
cause the cylinder wall damage.
No compression at all?? Did you perform a compression test yourself or did the previous owner?
If you haven't done it it then that's where I would start then do a spark test on all cylinders.
no compression on one cylinder may be a blown head gasket.
If the previous owner was running a 30:1 fuel oil mix then the problems started there, but maybe someone else will
jump in here with more advice.

 

[tpenfield]

Re: Seller blames me for loss of compression

Well, from the seller's perpscetive . . . you bought the engine 'as is', right?

So, was the compression know to be good or bad when you bought it?

a 50:1 oil mix should be fine, but you will need to verify that against was is specified for that engine.

 

[Frank Acampora]

Re: Seller blames me for loss of compression

50 to 1 is the correct fuel/oil ratio. Usng US measurements, I mix 1 pint oil to 6 gallons gasoline for a 48 to 1 ratio--easier to measure.

Now: These three cylinder engines will start and run on two cylinders so if he started it for you there is no saying that the compression of the top cylinder was good or not. Unless you performed a compression test at the time of purchase there is no way to know whether or not you or the seller damaged the engine.

Unfortunately, as stated above: If you bought the engine "as-is" then you have no recourse. You own the engine and repair costs are your responsibility.

At 0 PSI compression, it could be a broken head gasket or it could be a damaged piston due to lean running on that cylinder. A head gasket is about 30 dollars. If a piston is damaged then the engine will need to be disassembled, bored oversize on that cylinder and an oversize piston installed. Boring usually costs about 65 dollars and a new piston costs about 125. You should be able to do the disassembly and reassembly of the engine yourself.

 

[jerryjerry05]

Re: Seller blames me for loss of compression

Should have,would have,didn't have!!
A qualified mechanic should be used when buying ANY outboard.
If you didn't have the motor checked when you bought it and it NEVER RAN RIGHT,then it probably came broken!!!
You ever run it?
AS IS,is AS IS!!

 

[volundur]

Re: Seller blames me for loss of compression

Hi! thanks for you kind replies.

I'm pretty new to the whole boating scene, and I've already learnt a good lesson on evaluating the state of an outboard before buying / shipping. I obviously should have asked for compression tests on the engine beforehand, or at least tested it before running it myself.

I did test the compression myself yesterday and the top one is clearly dead.

Regarding the seller, I totally think he is a nice guy and did not try to screw me over, if the fault is his - he would simply not have been aware of the situation. Yet another reason for trusting the compression measure rather than a convincing truth from a nice fellow

I have two questions now:

1:
I'm a little confused that you guys say it would do damage to run the engine with to much oil in the mix. I kind of thought that 2 strokes would just love oil, and it would just burn if the mixture was to rich. - could you maybe explain what the damage would look like?

2:
is it possible that the piston rings are gone / stuck?

Thank you so much, ive been lurking and reading this forum for weeks now

 

[volundur]

Re: Seller blames me for loss of compression

Should have,would have,didn't have!!
A qualified mechanic should be used when buying ANY outboard.
If you didn't have the motor checked when you bought it and it NEVER RAN RIGHT,then it probably came broken!!!
You ever run it?
AS IS,is AS IS!!

yeb! I'm totally with you on that!
But I didnt buy it 'as is' since the owner told me it worked like a charm (except for a broken trim motor). I trust the guy is a decent man, and that we will find a nice solution

 

[Frank Acampora]

Re: Seller blames me for loss of compression

Depends upon your definition of damage. Old outboards ran at ratios of 16 to 1 quite happily so too much oil to a degree will not damage a modern engine. It will, however, cause fouled sparkplugs, poor mileage, and carbon plugged exhaust ports. It can cause a leaner running mixture but at the ratio mentioned this will be minimal and I would not expect any damage from lean running.

Broken or stuck piston rings usually result in compression ratios of about 20-60 PSI. At 0 PSI it is almost certain that either the head gasket is broken OR the piston is melted due to a lean run.

As far as the seller being decent---when it comes to money, no one is decent. Even family will screw each other for it. And remember, even Hell's Angels are nice guys until they stick the knife in your ribs.

 

[Justinde]

Re: Seller blames me for loss of compression

Following along here-

I understand that the carb link and sync is paramount to the engine running correctly. So, you can lean or richen the mixture with the carbs. I understand that, but, if, you run an oil rich fuel mix, how could you possibly run lean, no matter the adjustment in the carbs? Does the adjustment throw more air in the mix, thereby leaning the mix, or am I off target here. Point being, can you run rich fuel and have the carbs a bit off to protect your engine. Don't mean to 'hijack' a thread as such, just reading the above made me curious.

 

[volundur]

Re: Seller blames me for loss of compression

Depends upon your definition of damage. Old outboards ran at ratios of 16 to 1 quite happily so too much oil to a degree will not damage a modern engine. It will, however, cause fouled sparkplugs, poor mileage, and carbon plugged exhaust ports. It can cause a leaner running mixture but at the ratio mentioned this will be minimal and I would not expect any damage from lean running.

Broken or stuck piston rings usually result in compression ratios of about 20-60 PSI. At 0 PSI it is almost certain that either the head gasket is broken OR the piston is melted due to a lean run.

As far as the seller being decent---when it comes to money, no one is decent. Even family will screw each other for it. And remember, even Hell's Angels are nice guys until they stick the knife in your ribs.

Thank you Frank, your insight is very important to us, both the engine skills, and the people skills I guess youre right; I don't even know the guy who I got the engine off.

I have one more question:
If the head gasket is gone, and lets assume it's the only thing thats wrong - would I be able to see the air pushing out of underneath the head? I'm thinking something similar to using soap to identify leaking tires, or does a broken head gasket introduce complications that would not be obvious?

Thanks again!

 

[Frank Acampora]

Re: Seller blames me for loss of compression

Well, Justin: You need to vary from the mixture very significantly--remember that break-in is usually a couple of six gallon tanks of 25-1. However, usually at break-in you do not use wide open throttle.

Again, analyse this mentally: The high speed jet LIMITS the amount of fuel/oil mix delivered to the engine at full throttle. The gasoline vaporizes and the oil assumes small droplet form which lubricates the crank and bearings. The limiting factor is how much air the engine can pump, not how much fuel the carb can deliver. For best power we always want to run slightly rich to assure that all the available oxygen in the air is used to burn the fuel.

Now: The more oil in the mixture, the less gasoline. The correct air to gasoline vapor mixture is between 12 and 16 to 1 by weight. IF you have too much oil and thus less gas delivered, in the cylinder, the mixture can go beyond the 16 to 1 ratio causing a lean mixture.

BUT: Since all cylinders are running the same mixture, the engine will lose power and perhaps no damage will be done. Then again, perhaps all cylinders and pistons will be damaged. This is a situation that I personally have never encountered so it is all conjecture.


A broken head gasket will pump air into the water jacket and will not be obvious from the outside of the engine. A small break will pump hot gases into the cooling jacket and may cause overheating. With 0 PSI compression I would not expect overheating because there is no mixture in the cylinder to burn, thus no hot gases.

 

[Lone Duck]

Re: Seller blames me for loss of compression

Head gasket, top end crank seal or loose sp plug will also lean it out. You would think stuck rings or damaged piston would make a heck of a racket.

 

[volundur]

Re: Seller blames me for loss of compression

My hat is off for you guys. Thanks for answering with respect and knowledge each time.

 

[jerryjerry05]

Re: Seller blames me for loss of compression

Head gasket, top end crank seal or loose sp plug will also lean it out. You would think stuck rings or damaged piston would make a heck of a racket.

Too much oil can and will cause carbon buildup and that will sieze rings,all with no noise.
The only times I hear any racket is when the damage is so bad the rod or bearings have gone.
The stuck rings will eventually start scraping the walls and cause a hot spot and melt the piston and then the ring breaks up and the party really gets going!!! Wiping out the rest of the piston and head and then working it's way to the bearings!!!