Define "Scored Cylinder"?

[turtle1173]

Hi all,<br /><br /> I have a compression problem in my 1972 85HP Chrysler. The low cylinder has been registering around 70 while the others are around 127. After some testing I figured it was the head gasket.<br /><br /> I just pulled the head and sure enough, the metal ring around that cylinder is broken on the bottom.<br /><br /> All 3 cylinders have light scratches on them (some worse than others). Is there any reason to concern myself with this or should I just replace the head gasket and go on?? How do you define a "scored cylinder?" Any scratches or just gouging?<br /><br />Thanks,<br /><br />Shane

 

[mjake]

Re: Define "Scored Cylinder"?

I have gone through this several times. Twice on GT 150 and now on 2000 Ficht 200. I just scored one but to do a job right you should do all. You will have to have it bored and put new pistons. Probably looking around 3 grand. Don't just put head casket on and go. you will never make it out on the water very long if ever. Just my opinion. Sorry about it and good luck.

 

[BF]

Re: Define "Scored Cylinder"?

Hi Shane,<br /><br />Now for the counter point... To me, it depends what you mean by "light scratches". In a 30+ year old motor I'd expect to see some wear marks since the rings do rub up and down the cylinder. But if they're more gouges then scratches I might be more inclined to do something about it. <br /><br />If you were inclined to take it further apart, you could see the degree of wear on the rings. You could lightly hone the cylinders and put in new rings for not much $$. Especially if you know the rings are original you might wanna think about that. But I wouldn't overbore 'til it broke down (too much $$$ for the engine you're talking about). Mind you I do my boating on freshwater lakes and a break down would be a PITA but not dangerous. But, my guess is that if you were paranoid about reliablility you'd be running a newer rig anyway. <br /><br />I'm no outboard guru, but that's my $.02 anyway.<br /><br />Brent

 

[dkondelik]

Re: Define "Scored Cylinder"?

'afternoon turtle,<br /><br />if you're reading 127 on the others AND you know which end of the screw driver to hold AND if you can find a trustworthy machine shop near by AND if this motor means alot to you. then go ahead and fix it. due to its age and lineage, it has very little resale value so don't bother fixing it to sell. you wont get your money back.<br /><br />all of that said, if you tear down the motor yourself , i'd just hone the good cylinders & re-ring those pistons (if the scoring isn't too deep) as for the bad cylinder. probably have to over-bore and purchase oversized piston. I think weisco can supply pistons for you. the machine shop can probably bore THE cylinder for about $100 if you bring in the block (and the new piston to size it too)<br /><br />others here can offer more info.<br /><br />Good Luck

 

[turtle1173]

Re: Define "Scored Cylinder"?

So does anyone think that the lower compression is due to the broken ring on the head gasket? Or just from the light scoring?<br /><br />Shane

 

[Chinewalker]

Re: Define "Scored Cylinder"?

Simple - replace the head gasket and recheck the compression... If all three come up around the 127 you measured first time out (no more than 5% difference), you should be good to go...<br />- Scott

 

[Terry H]

Re: Define "Scored Cylinder"?

Do as chinewalker says...should be just fine...clean and flatten both surfaces...head and block...put in a new head gasket, by the book, and you should be good to go...just a Thought

 

[DJP]

Re: Define "Scored Cylinder"?

Klondike7...are you suggesting that he bore just 1 cylinder and forgo the rest ? I know that's not what you meant. That's not what he meant.

 

[BF]

Re: Define "Scored Cylinder"?

To clarify, I think the compression drop was from the broken head gasket! I'd guess the scoring/light scratches/marks might be just from normal use (?), but IF you wanted to go the next step without big $$$, you could probably just lightly hone all 3 cylinders and check/replace the rings only, and I mean rings on pistons, not the rings on the head gasket. H.G. will be new no matter what else you do - if anything. Then at least you'd know you're not running on nearly worn out rings. But it's boating season, a new head gasket would probably get you going again. As suggested, you could do the gasket and then check compression, to see whether you're happy enough.<br /><br />HTH<br />Brent

 

[turtle1173]

Re: Define "Scored Cylinder"?

Thanks for all the responses guys!<br /><br />I've got another question that maybe you all can help me with. How do I access the thermostat on this head?? There are no bolts on the front housing. The housing looks to be built into the head. At first I thought I could just insert the thermostat through the back side but that isn't possible. There is a small bolt to the left of each spark plug hole. I have removed them and thought perhaps that top cover comes off. Does anyone know how to get at this? By the way, when I removed the head, there is no thermostat in there!<br /><br />Thanks again,<br /><br />Shane