Volvo Penta 4 cyl I/ Compression variance and overheating

[99FourWinns]

Hi everyone I am new to this, so I hope I am posting correctly. I recently acquired a 99 Four Winns horizon 170 with a 4cyl Volvo penta I/O. An inspection report was done, and I wanted to a get a little help on finding a solution to some of the issues.

The report says that it idles well and runs rough (due to carbs needing adjustment). The compression is as follows;
1- 185, 2- 165, 3-120, 4- 125. Note says frost plug on water jacket was out and it has been pounded back in. The cooling system was tank tested, and it said it starts to overheat, and has a weak water pump and tell tail. It is currently winterized.

*I have attached the full inspection link*
http://https://www.dropbox.com/s/a3p7kwntqqrm9ge/1234712.pdf

I have done many repairs on cars but this is my first boat, so any help on knowing where to start and what may be causing some of my issues would be great. Thank you.

 

[Scott Danforth]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

based on the compression, there is an issue.

based on the core plug being out, it was most likely not winterized properly, and probably has a crack in the block.

they are core plugs, not frost plugs

 

[Bondo]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Hi everyone I am new to this, so I hope I am posting correctly. I recently acquired a 99 Four Winns horizon 170 with a 4cyl Volvo penta I/O. An inspection report was done, and I wanted to a get a little help on finding a solution to some of the issues.

The report says that it idles well and runs rough (due to carbs needing adjustment). The compression is as follows;
1- 185, 2- 165, 3-120, 4- 125. Note says frost plug on water jacket was out and it has been pounded back in. The cooling system was tank tested, and it said it starts to overheat, and has a weak water pump and tell tail. It is currently winterized.

*I have attached the full inspection link*
http://https://www.dropbox.com/s/a3p7kwntqqrm9ge/1234712.pdf

I have done many repairs on cars but this is my first boat, so any help on knowing where to start and what may be causing some of my issues would be great. Thank you.

Ayuh,... Welcome Aboard,... Yer link is Dead,...

With a core plug pushed out, It most likely wasn't winterized at some point in it's history,...
So long as it ain't gettin' water in the oil, No biggie,...

I guess I'd change the impeller, 'n fix the coolin' problem,...

While it's compression ain't the greatest,...

I'd run 'er til she pukes,...

 

[99FourWinns]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Hi, thanks for the reply.

I thought about the block being cracked, however on the inspection report in the spot to check off that the block is cracked or leaks and the gasket is bad or head cracked, its not indicated.

I quoted the inspection report with "frost plugs." Good to know they are called block plugs on a boat.

Would the compression #'s have anything to do with the carbs being out of adjustment?

 

[Bondo]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Hi, thanks for the reply.

I thought about the block being cracked, however on the inspection report in the spot to check off that the block is cracked or leaks and the gasket is bad or head cracked, its not indicated.

I quoted the inspection report with "frost plugs." Good to know they are called block plugs on a boat.

Would the compression #'s have anything to do with the carbs being out of adjustment?

Ayuh,.... It's got nothin' to do with Boat motors,...

It's a common misnomer,....

They're there, so the sand from castin' can be removed,... hence, it's a Core plug,....

Over the years, they've come to be known as a Frost plug, because when a block freezes with water in it, they blow out from the ice expandin',...

It's not why they're there though,...

 

[99FourWinns]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Sorry about that. I'll try to attach the report instead

what should the compression be on this type of engine, and what can I do to get it back there?

 

[Bondo]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Sorry about that. I'll try to attach the report instead

what should the compression be on this type of engine, and what can I do to get it back there?

Ayuh,.... Compression on this motor is 'bout the same as any other motor,...

150psi, 'n above is a newish motor,...
Anything at or below 100psi is a rebuildable core motor,...

You'd have to do a leak-down test to see where the compression is bein' lost,...
If it's a valve sealin' issue, a valve job would fix it,...
If it's leakin' past the rings, a motor rebuild would be in order,...

Like I said, I'd just Run it, 'n worry 'bout it later, when there's Really an issue,...

Run time, is sometimes another way for things to break-in, 'n settle down,....

 

[insttech1]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Look in the "adults only" sticky and read about compression testing.

That test report only tells one side of the story: they're not in spec'. (I "think" from best to worst PSI should be within 10%, but look it up.) But doing another one dry, and then w/ three squirts of oil in each cylinder, should tell you whether it's the rings or the valves.

185 seems pretty high, but I guess not outside any realm of possibility. 125 is pretty low.

But if the block is actually bad (not a good sign from the freeze plug), then you might want to just look up Michigan Motorz or other sources for a long block replacement, and not have to worry about compression numbers anymore....:joyous:

That report "looks" like the ones on xbay for the place around Wisconsin that auctions off repo's and fixer-upper boats. You'd better plan on putting at least some money into it......but if you got it for a decent price, then it's a good project, and easy to work on.
The rest of the report says it's in good shape.

A carb rebuild is easy, and probably quite necessary, and will cost you about $45 for the kit (get the actual Holley Marine kit).

Let us know how it goes.

 

[99FourWinns]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Thank you guys for all your help. I will start with the impeller and see how it goes. I'll let you guys know how it goes. Any other suggestions, I'm open to them.

 

[jerryjerry05]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Some one suggested a bit of oil in the cylinder and then another comp test.
Also use a deifferent guage and see if the results are the same.
If the core plugs were popped out???It's possible the block could be cracked.
What condition were the plugs in when you pulled them?
Any rust or corrosion?
If the manifold wasn't drained? it's possible the manifold cracked and leaked water into the cylinders?
Pull the manifold and check for damage.
The motors about 25 years old.The manifold could be shot.
Since it's running. Get it hot and add some Marvel Mystery Oil and let it set for a few days.
Check the gas for water.
Alway add the model # something like 3.0GSM or what ever it is.
Will help make sure were looking at the right motor.
Change the impeller.

 

[99FourWinns]

Re: Volvo Penta 4 cyl I/ Compression variance and overheating

Here is an update on my situation, I know it's been awhile. I finally picked it up from the seller and I dropped it off at a reputable repair shop. I had them go through the whole boat (Spring start up). Despite the core plug being out previously, the engine was inspected and was not cracked anywhere. The exhaust manifold gasket was bad causing the overheating (now replaced), The bilge pump vent hose was melted (now replaced), impeller replaced, optimum marine battery installed with new tray. Nothing wrong with the carb. A trailer roller replaced. According to the shop it runs very well. I will pick it up tomorrow. I'll have to see for myself when I can get it on the water.

Thanks everyone for all of your help.