new rings// compression 60 both cyl.

[ryanc]

Intalled new rings, lower crankcase bearing and oil seal, compression on both cylinders at 60. Boo-hooooo <br /><br />did I loose a seal on the crankcasing???

 

[Paul Moir]

Re: new rings// compression 60 both cyl.

I wouldn't assume anything until you're broken in. When I did my brother's little 4hp, compression went from 90 after rebuild to 130 after break-in by my guage.<br /><br />Did you hone out the cyls?<br />Exactly how did you test compression? How many pulls?<br />What did you read before rebuilding?<br />Did you measure the cylinders?

 

[ryanc]

Re: new rings// compression 60 both cyl.

Thanks paul for your reply, measured everything looked to be okay, did not hone cyclinders,just changed out rings, bearings.<br /><br />When motor coughs I found water escaping out of hoses that go into the block?? Could this be a pressure lost???

 

[ryanc]

Re: new rings// compression 60 both cyl.

Paul, when motor coughs water is popping out of small hose fittings that screw into the side of block, can I be looseing pressure here??

 

[pjc]

Re: new rings// compression 60 both cyl.

first issue you need to do ryanc is to go to local library and get book regarding basics on internal combustion engine. READ SAME. Then attempt to do engine work. I am very frustrated by posts asking if a water hose is related to combustion / engine performance. Seems to me there are many folks simply stuffing parts into motor expecting like new performance. These same folks should be having their repair shop, etc do the work these people are not qualified to do.<br /><br />Perhaps do it yourself TV is responsible for this????

 

[Paul Moir]

Re: new rings// compression 60 both cyl.

ryanc - I hate to say it, but not honing your cylinders would certainly explain your poor compression. And also your new rings will never seat properly if it's not done. I seriously reccomend you break down the engine again and do that first.<br />There's a good post about honing here somewhere. I'll find it, since the process is usually inadequatly explained in most manuals. That shiny, glazed finish you saw inside the cylinders will not hold oil, and actually prevents a good seal. The bores must be a very little bit rough.<br /><br />Actually, before you do that:<br />Are you sure water is coming out of those fittings? The ones that are there to recirulate oil back to the intake manifold? (help me a bit here, I'm really not familiar with your engine)<br />If so, you're getting water into the crankcase! Did you obtain a inch-lb reading wrench for those head gasket bolts? I'm thinking water is leaking into the cylinders from the head gasket, and leaking back into the crankcase somehow. Why aren't hoses attached to those fittings? Having them unconnected will allow air to enter the crankcase, leaning out the mixture and causing that sneezing.

 

[ryanc]

Re: new rings// compression 60 both cyl.

Paul, thanks for your reply<br /><br />Okay, 1973 merc 200 20 hp. I do not have perse a head gasket but rather a water jacket gasket that fits over the plugs which are sealed good.<br /><br />my mistake, it is not water but gas-oil that comes thru the hoses into the side of the head with brass fittings that have like a jet that goes into the cyclinder.Hoses look to be 1/8 inch inner diameter. <br /><br />I have another head that I may swp out with compression 125/124 on cyclinders(so the fellow said that I bought it from".<br /><br />Is there a way to check compression on head separated from every thing else, like useing a air wrench to turn the crank shaft??? Hate to swap out and find another problem, thought about opening the crankcase just to look at bearings.<br /><br />well, anyway I am having trouble finding hose, do the marina's carry this small hose in stock?? Thanks for your help and time.

 

[Paul Moir]

Re: new rings// compression 60 both cyl.

Ah, all clear now. <br /><br />The engine is almost defintely sneezing due to those recirc lines being open. You need some fuel safe hose to replace em with. A local small engine repair place will have it in those sizes. Home Depot up here used to carry it (orange line) but does not any more. Mabey they still do in the 'States? Whatever hose you use, you must be certain it is fuel rated, or gasoline will melt it.<br />(PS - gasoline melts silicone too)<br /><br />If you can figure out a way to spin the engine, you can take a compression check. It's going to be pretty hard on that size engine without some advantage though. Mabey you can borrow the flywheel off your runner and wrap a rope around it?<br /><br />Personally, I'd keep going with your freshened engine, and keep the other one for backup. What's the fun of bolting an old powerhead and running that? <br /><br />I'll find that article...<br /><br />Oh, it's right here. The trick is to only do it for a few seconds, and with a slow drill (2 or 3 rotations per second). You do *not* want to change the size or shape of the hole, just give it a scratched surface.<br />Your pattern should look like this.

 

[ryanc]

Re: new rings// compression 60 both cyl.

Paul, cylinders were not scored, nor dingy brown- yellow haze. Motor was not used all that much by old grandad. I got the hose at Pep Boys(gas) and am working on it now.<br /><br />I read the debate concernig dingleberry hones,flex hones ect, I wouldn't even begin to use something like that free hand, not with my luck.<br /><br />now the thing concernig muriatic acid and washing it out quickly seems to me to be the lesser of two evils for a newbie as myself.<br /><br />anyway will get the hoses back on. Being that there was a really tight fit in getting hose fitting off the head, I removed an accessory plate on side of engine, a place you can see the pistons and or check for broken rings. Trouble is the gasket is gone now, CAN I use some high temp silicon type gasket maker to reseal??? cause I don't beleive i will find this particular gasket. thanks again for your reply,

 

[Clams Canino]

Re: new rings// compression 60 both cyl.

You *have* to hone it with *something* to get the new rings to seat to get your compression up.<br /><br />Take it to a machine shop for honing if need be.<br /><br />-W

 

[BlackKnight755]

Re: new rings// compression 60 both cyl.

Ryan,<br />You really do have to hone it some way so that the rings will seat, if you don't, don't look for the compression to change for the better. As clam said if you have to, take it to the machine shop to have it honed out. Take it to someone or attempt it yourself, for if it isn't done POSITIVELY those new rings won't seat. <br /><br />Also, I don't know how much acids you have ever worked with but I think I would think up another route than acid. this is just my Humble Opinion.<br /><br />Good luck,<br />BK

 

[ryanc]

Re: new rings// compression 60 both cyl.

Hello.... Last night i found some gas hoses that lead into the cylinder, they were leaking gas bad. This of course was causing me to lose alot of compression (i assumed). Anyway fixed hoses and put a new gasket on this plate where you place a starter...Today i did another copmpression check and both cylinders read 100psi even!!!! ain't that something. I didn't evn horn out cylinders. Those rings are sitting right.She ran just like the day she came from the factory!!! Now we are going to test her on the water. Wish us luck!! robert/ryan

 

[Paul Moir]

Re: new rings// compression 60 both cyl.

The acid was for cleaning aluminum off the walls. Since your pistons are intact, you won't be needing to do that.<br /><br />You absolutely must have those holes honed if you're unwilling to do it yourself.

 

[emckelvy]

Re: new rings// compression 60 both cyl.

Ryan, I think your Chinese Compression gage is in question. Readings just don't change that drastically overnight.<br /><br />Let us know how it runs.

 

[ryanc]

Re: new rings// compression 60 both cyl.

Hello, yes Ed you are correct about the compression tester, I used another fiting on tester and got a reading of 100 psi on both cylinders.<br /><br />Replaced the recirculating hoses on block and pulled there pipe fittings and resealed. Took her out for three hours and came back .She ran fine after getting the idle mix adjusted correctly and motor quit coughing and purred at idle.<br /><br />Only problem was it planes the boat fine with two people plus heavy marine battery ect but not with three people.<br /><br />Got home and rechecked again the compression was the same 100 psi.<br /><br />I have another head from ebay whom the seller says has compression of 1230/131 psi. I may just throw this one on and take it from there.<br /><br />Now for the honeing. I am not rich and cannot afford to pay someone for a honeing, as far as I am concernig if I had the money I would be better off getting new oversized pistons and then pay for a new drilling.<br /><br />antway, I am not real comfortable with a slow drill roughing up the cyclinder walls, but would be willing to try the acid wash as long as i could use a baking soda solution or another akaline solution to rinse to neutralize the acid. Need more info on this technique.<br /><br />Why can't i just take some 200 plus emory cloth and lightly work around the cyclinder wall?<br /><br />Thanks for your time ,helf and expertise.

 

[ryanc]

Re: new rings// compression 60 both cyl.

Whoops the compression on spare head is 130/131 so I am told. Can I check compression on the bench useing a impact or air wrencg to turn the crankshaft safely??

 

[Paul Moir]

Re: new rings// compression 60 both cyl.

A cylinder hone tool costs less than $30, whereas pistons are around $100 each. <br />Most places charge around $15 a hole to hone. You could probably even get a local garage to do it for you. This stuff isn't rocket science.<br /><br />Do not try inventing any other method! Acid is not for honing! Neither is baking soda! Leave the emery cloth for plumbing!<br /><br />The acid was used to clean chunks of melted aluminum off the (cast iron) walls of that engine. It was not used for honing it!

 

[ryanc]

Re: new rings// compression 60 both cyl.

Thanks Paul, ya don't like my ideas? ha ha. What in the world did they do back in the old days when they didn't have all the fancy electric tools ect, how did the oldtimes get it done??<br /><br />where do you find a hone ? do they come in different sizes? and exactly how easy is it to mess up every thing?? Would my car mechanic be able to hone it ?? thanks for your replies and directions

 

[Clams Canino]

Re: new rings// compression 60 both cyl.

Your car mechanic should be able to hone it yes. Any machine shop can too. Mine gets $7 a hole but I do my own.<br /><br />-W

 

[jimmy@wm]

Re: new rings// compression 60 both cyl.

I agree with the other guys on the honing issue. I'm not too familiar with boats but I grew up around rebuilding car and and other engines. The rings will not seat right if something is not done to these cylinders. It's alot cheaper to do it now than later. My dad always said when rebuilding cars to his customers who were a little reluctant to pay an extra few dollars to have something fixed right " Pay me now or pay me later, pay me later, pay me greater".May sound cornny but it's true. Just my opinion.<br /><br />Jimmy