need some help Late 70's 85 hp chrysler

[gtpcompG]

i have a bit of a problem got a boat, motor, and trailer cheap but the motor has little to no compression in the second cylinder ,,, i feel more back pressure then compression other two cyl feel like they have lots where should i go with this, do these motors have a common problem like this, i would like to fix it its in great shape other then this problem.....
would love some help
Steve

P.S. My email is g.tpcompg@hotmail.com

 

[rudedude]

Re: need some help Late 70's 85 hp chrysler

If the motor runs ,what you need to do is use a compression tester on it. Turning the motor by hand isnt a good check of compression at all. Make sure you do not turn the motor counterclockwise, you will damage the water pump impeller. Once you get the compression check out you should change out the impeller.

This forum will have many members willing to help you do that. But for now lets get the compression checked correctly.



Welcome to iboats.

 

[Frank Acampora]

Re: need some help Late 70's 85 hp chrysler

Well, GTP. Most of the time when these engines are damaged, it will be so severe that there will be little to no compression on the damaged cylinder. So the first quick and dirty test is to remove all spark plugs. Put your thumb over each plug hole while turning the flywheel. Each cylinder will either have compression or not. If any cylinder does not have compression, then don't worry about other tests--the engine needs a rebuild.

If all cylinders appear to have compression, then the next step is to actually check compression levels with a good quality gauge to determine the approximate condition of the engine. We would be looking for say, over 100 psi with all cylinders being essentially equal. (new would be around 140-145 psi)

If all cylinders are relatively high and fairly equal--say within 10 pounds, then enjoy running your boat on the river or lake.

If compression varies by more that 15-20 psi then again, it's time for a rebuild.

Since you can re-bore a single cylinder and replace only a single piston if needed, these engines can be relatively inexpensive to rebuild. And since for the most part, only hand tools are needed, it is a relatively easy job--even for the inexperienced with some guidance.

So go do the quick and dirty and take it from there.