1988 50hp Force No Compression

[trex3648]

I have a 1988 50HP Force. It has sat for fifteen years and only has 15 mins on the motor. I have added about six hours to it. However, on the last run the engine lost power (Like it was running out of gas) and started smoking. I immediately shut it down and got towed to the boat ramp. I checked the compression on the cylinders (2 cylinder) and found the top cyclinder had no compression and the lower cylinder had about 25lbs of compression. After reading for several hours on this web site (which I think is just excellent) I concluded that maybe the head gasket went bad. However, I would like to confirm this. Can anyone out there give me suggesitons on how to confirm the bad head gasket? Also, it appears as though I am not getting any spark at the plugs. I also would like a recommendation on a good, reasonably priced, repair manual. Note: The motor is on a 14.8ft, v-haul bayliner. Top speed with only myself in the boat was just 21.5mph.<br /><br />Thanks,<br /><br />Trex3648

 

[seldont]

Re: 1988 50hp Force No Compression

0 lbs on one and 25 lbs on the other sounds very low. Almost like you may have a faulty compression gauge. I would be tempted to try a diffent gauge. The easiest way to confirm the head gasket to me would be to pull the head. On that 50 hp it oughta be a piece of cake.

 

[Drowned Rat]

Re: 1988 50hp Force No Compression

It sounds like a head gasket for sure. Other problems could be broken or faulty valves, but you would hear them making a racket ,or bad rings, but again they would make a racket and it would be unlikely for either of these to go bad after only 8 hours. The head gasket probably dried out after 15 years on the shelf and gave way.

 

[alcan]

Re: 1988 50hp Force No Compression

Broken or faulty valves?? A head gasket sounds like a good place to start looking in this case. After the lay up did you service the water pump before use? I bet you didn't. I bet the motor over heated and there went the head gasket.

 

[catfish1]

Re: 1988 50hp Force No Compression

if it had been sitting up for 15yrs chances are the rings were stuck.

 

[trex3648]

Re: 1988 50hp Force No Compression

Originally posted by seldont:<br />0 lbs on one and 25 lbs on the other sounds very low. Almost like you may have a faulty compression gauge. I would be tempted to try a diffent gauge. The easiest way to confirm the head gasket to me would be to pull the head. On that 50 hp it oughta be a piece of cake.

 

[trex3648]

Re: 1988 50hp Force No Compression

All,<br /><br />Thanks for the information. Yeah, you are right I did not service the water pump. The compression guage is brand new; so, I doubt if it is bad; still, I will get another one and check. I heard no unusual noises. Is it a good idea to go ahead and replace the piston rings, valves, etc? And, should I machine the head (do not even know if this can be done) since most likely I over-heated the engine? Also, I have read where others have referred to a "over-heat buzzer" or something like that. I did not hear any warning buzzard. Again, thanks for all of the information. I really appreciate it.<br /><br />Trex3648

 

[seldont]

Re: 1988 50hp Force No Compression

Originally posted by alcan:<br />Broken or faulty valves?? A head gasket sounds like a good place to start looking in this case. After the lay up did you service the water pump before use? I bet you didn't. I bet the motor over heated and there went the head gasket.

Guys I may be wrong but it seems to me that a bad head gasket would still leave some measurable compression in both cylinders. Zero compression on one sounds like a complete piston failure. I may be wrong on that just seems odd. However compression that low would certainly warrant pulling the head to investigate the problem. If it is a head gasket you had to replace it anyway and if it is something more you may or may not want to repair it. I do not think you will know for sure until the head comes off. IMHO.<br /><br />By the way if you do repair it I would check the overheat sensor and make sure it is working properly as well as servicing the water pump impeller. Good luck either way......Seldon

 

[roscoe]

Re: 1988 50hp Force No Compression

I prefer a manual by Clymer's.<br />Or even better, an original factory service manual.

 

[WhiteHorse]

Re: 1988 50hp Force No Compression

All good input from the guys above. Definately pull the head and investigate. After sitting that long, there was several things that should have been checked/serviced. <br />1) The impeller. Was the motor peeing water while it was running? Did the overheat alarm sound at all? <br />2) Carb That should be a single carb model, was it cleaned prior to the run? <br />3) I hate to ask this, but you don't sound too outboard savvy, so... Did you mix 2-stroke outboard oil in the fuel before running it? What ratio? If it ate up the rings in both cylinders that quick, it sounds like it either had no oil, or was getting no oil. <br />4) How many hours were on it? If this motor had never been put through it's original 10 hour break-in with double oil mix then you were out there running the sheebeez out of it at over 3K rpm and ate up the rings and cylinder walls. These motors are suppose to be run at less than 3200rpm, with double oil mix, for the first 8-10 hours of their life. <br />5) Like the guys above said, the rings could have been stuck.

 

[trex3648]

Re: 1988 50hp Force No Compression

Thanks Skye at White Horse Marine and Seldon. Yes, I am not outboard savvy; still, I did use 2-stroke oil in the gasoline at a 50:1 ratio. However, I did not know about the 8 - 10 hour break-in and this was never done. The motor has less then 10 total hours on it. I was ran for about 15 minutes when new then it sat until December of 2003. Since December of 2003 I have logged about 6 to 8 hours on the motor. I never heard an alarm; so, I will check this. Water was coming out of the two exhaust ports. Yes, it is a single carb system and no it was not cleaned prior to run. What physical signs should I look for when I look at the piston. And, if the rings were stuck wouldn't the pistons also be stuck? Seldon: you say that the motor is not worth fixing if I have to replace the pistons? Why is this?

 

[DJ]

Re: 1988 50hp Force No Compression

trex3648,<br /><br />You ar at the point now where removing the head is just about a necessity.<br /><br />With readings that low, you will probably see something obvious when the head removal is completed.<br /><br />BTW, 2-cycle engines do not have valves like an automobile engine. They have what are called reed valves or plates. I doubt, very much, that those failed.

 

[seldont]

Re: 1988 50hp Force No Compression

Depending on what is wrong with the engine after you tear it down you may decide you do not want to spend that much money on a 16 year old 50 horse motor. On the other hand you may decide to go ahead and either repair it yourself or have it done. If you are handy with a set of wrenches??? It all really depends on what is wrong when the head comes off. Compression that low almost sounds like a major piston failure. First things to look for when you pull the head will be of course a blown head gasket and then make sure the tops are not melted out of the pistons. Provided the tops of the pistons are not damaged I would pull the exhaust cover and look at the sides of the pistons through the ports in the cylinder walls as well as rotating the crankshaft and looking at the cylinder walls to see if the is any evidence of scoring. For the compression to have gone that bad that quickly some BIG happened it would seem. Also check the head to make sure it is not warped or cracked. And while you are looking through the exhaust ports rotate the engine til you can see the piston rings through the ports and then push on them with a screwdriver and see if they have and tension in them. When you push in on them they should spring back out against the Cylinder wall. Not knowing you motor or situation I cannot judge if you want to repair it or not. But the cost of repairing a major failure such as burned pistons may easily exceed the cost of a good used motor of the same size unless you can do the work yourself. Sorry so long and good luck...Seldon

 

[seldont]

Re: 1988 50hp Force No Compression

By the way if you are reasonably good with a set of wrenches that little 50 horse Force will be about as easy to work on as they come.

 

[catfish1]

Re: 1988 50hp Force No Compression

after you pull the head, if you find chunks of ring material jammed into the top of the piston and dont want to bother rebuilding it, you could probably get some pretty decent money out of parting it out! especially if it has as little run time as you say it does. those motors are usually worth more in pieces than they are whole and running.