1998 40hp force 60lbs compression on 1 cylinder

[3nails4life]

I have a 1998 40hp force with only 60lbs compression on 1 cylinder and 120 on the other. My question is this is it worth the cost of repairing this engine or should I consider replacing the engine?

 

[foodfisher]

Re: 1998 40hp force 60lbs compression on 1 cylinder

That would depend on the reason for the low reading. I would try a decarb first.

 

[Big Fish Billy]

Re: 1998 40hp force 60lbs compression on 1 cylinder

I just bought a 1997 Force 40, I have my own problems but I took a compression test and have 135 in each cylinder.

 

[3nails4life]

Re: 1998 40hp force 60lbs compression on 1 cylinder

ok I have checked on how to decarb the engine the problem is it will not start or it will run as long as you have the key on.The last time I had it out it was very hard to start and once it started you would have to rev it up immediatley to get it going and it really ran ok then but when you idled it back down it would shut off do you think I could still do a decarb and how would you suggest I do it

That would depend on the reason for the low reading. I would try a decarb first.

 

[jerryjerry05]

Re: 1998 40hp force 60lbs compression on 1 cylinder

Don't worry about a Decarb
The compression is 60# off.
A decarb isin't gonna help when it's that bad..
The head gasket might be blown?
The rings shot and the cylinders scored?
Remove the head and check the gasket FIRST!!!
Then post your location.You might be close to someone who can help?
The cost miight be as low as $35 for a gasket.
It's a newer motor so repairing it might be worth it?
Sent you a PM

 

[3nails4life]

Re: 1998 40hp force 60lbs compression on 1 cylinder

Will check gasket this weekend

 

[Jiggz]

Re: 1998 40hp force 60lbs compression on 1 cylinder

Absolutely agree with Jerry. With compression reading that low, you'd be better off opening and inspecting starting with the head gasket. Keeping to run the engine at this condition can only aggravate the problem especially if the cause is a broken ring caught in one of the ports. However, if it is only a gasket problem, this is well worth fixing it.

 

[3nails4life]

Re: 1998 40hp force 60lbs compression on 1 cylinder

Thanks Jerry I checked the head gasket this morning and the top cylinder that had the 60lbs compression the metal ring that is part of the gasket is damaged with about a 1/4 to 1/2 inch gap. The piston walls on both cylinders are not scored at all I am going to replace the head gasket do you know the torque on the bolts? I was told there is a pattern to follow when tightening the bolts do you know if that is true and what it is? Anyway thanks again Jerry I am glad that I do not have to replace the motor now.

 

[3nails4life]

Re: 1998 40hp force 60lbs compression on 1 cylinder

Thank you Lieutenant Junior Grade as well

 

[pnwboat]

Re: 1998 40hp force 60lbs compression on 1 cylinder

Bolts should be torqued to 225 inch pounds. Below is a picture of the tightening sequence. Run the motor until it warms up, then check and re-torque if necessary after it cools down a bit.

 

[Jiggz]

Re: 1998 40hp force 60lbs compression on 1 cylinder

In addition to PNW's torque instructions, you also need to do it in at least two steps or even better three step torquing. What it means is instead of torquing each bolt to its final torque setting (225 inch-#) as you go through each bolt, torque each and all bolts initially to half of the required torque settings (around 115 inch -pounds) and then go back to the starting bolt and start torquing again but this time using the final torque setting (225 "-#). You can also do a three step torquing using 50%, 75% and finally 100% increment of the final torque settings.

 

[jerryjerry05]

Re: 1998 40hp force 60lbs compression on 1 cylinder

If you don't have an inch pound tourqe wrench.
The tourqe is 20# and like Jiggz suggest a 3 step tourqing is needed.
I start at 15 then 18 then 20.
Make sure the screw holes are cleaned out and the bolts too.
I use marine grease on the threads.

 

[3nails4life]

Re: 1998 40hp force 60lbs compression on 1 cylinder

Got it back together and it runs great. THANKS FOR ALL THE HELP