175 OS Glazed cylinder and low compression.

[DeonCarpenter]

I had my 98? Mercury 175 OS rebuilt. It was not running well so I had the engine serviced. The compression was very low on number five, 75 pounds. 100 on 1,3. 120 on 2. 115 on 4 and 6. The mechanic said that that #5 didn?t have fire, and that caused the cylinder to glaze. He replaced the power pack and said to run the motor and the compression would come up to normal in 10 hours or less as the motor was not completely broken in yet. Is this true? The motor has four months left on the rebuild warranty.

 

[emckelvy]

Re: 175 OS Glazed cylinder and low compression.

IMHO you better run this thing for 10 hours straight if you have to then send it back to the mechanic when the compression readings don't come up to "normal". Be sure to vary rpm up and down during this continuing break-in period.

I'm not really buying his theory. If the cyl wasn't firing, the fuel/oil mix is just gonna "wash" thru the cylinder and out the exhaust ports.

And, since that cylinder wasn't firing, how could it get hot enough to develop a "glaze"?

Granted that a new set of rings will probably break-in better if there's combustion pressure pushing down on the tops of the rings, but I've never heard of a cyl 'glazing' due to being fuel-washed.

If someone has actually experienced this phenomena, please enlighten!!

HTH & G'luck............ed

p.s. if after 10 hours all the compression readings don't even out, they're likely never gonna.

 

[CharlieB]

Re: 175 OS Glazed cylinder and low compression.

A leaking fuel pump diaphragm will 'wash down' a cyl and loose compression.

The excessive fuel washes the oil down. A running cyl evaporates the fuel leaving an oil film on parts. The washes down cyl wears the rings, piston and cyl walls.

Get 10 hours on it quickly so that you can return it!

 

[DeonCarpenter]

Re: 175 OS Glazed cylinder and low compression.

Thanks for your help. I thought they replaced the fuel pump diaphragm when they rebuilt it but I will ask. The shop is supposed to bring the boat back to me tomorrow. They said the starter went out on them but they were replacing it for free since it did it in their shop. They seem like good people. They did say they would tear the engine apart and hone out the cylinders but the mechanic said that would not be the best route. The engine has been on double oil since the rebuild and does not have 10 hours on it yet.

 

[DeonCarpenter]

Re: 175 OS Glazed cylinder and low compression.

I got the boat back form the dealer and it was running great. New power pack, and a new battery.
Just over five hours and it started making a rattling noise in the engine, not a knocking noise. I shut her down and paddled her in. It was late when we made it home so I have not run a compression check but I am guessing a broken ring. It was still on double oil.

 

[j_martin]

Re: 175 OS Glazed cylinder and low compression.

Lost a ring locator pin. I hate it when it does that!!

 

[DeonCarpenter]

Re: 175 OS Glazed cylinder and low compression.

I checked the compression and #5 was almost zero and there was grit on the plug.
I called the dealer and he said he would rebuild for me. It is starting to cool down here and by the time, probably a month before they are done with it will be too cold to take her out for a break in. I just hope the dealer, just a little guy, will extend my warranty.

 

[DeonCarpenter]

Re: 175 OS Glazed cylinder and low compression.

Ok it has gotten a little shaky now. I talked with the dealer I bought the boat from and he said the warranty runs out on 11/16/08. I know the salesman told me it was warranted for six months but the paperwork does say ninty days, I guess I should have read it better. They said they will rebuild it but the motor is on the warranty clock. They have had the boat more than me since I bought it and now they are talking six weeks to get the parts in. It may run out of warranty in their shop, then what?

Anyone ever had an issue like this?

 

[CraigC]

Re: 175 OS Glazed cylinder and low compression.

If it's in the shop now, it should NOT matter if it takes 6 weeks, or even a year to get parts, you brought it to them BEFORE the warranty expired with a problem. The date they took delivery with knowledge of the problem is the date they have to go by. They can't leave it sitting around for weeks and then tell you that you're out of warranty when they get around to working on it! I'd have a conversation with them before the warranty date gets here, but in NO way would I ever pay for anything knowing that I brought it to them with a problem before the warranty expired!

EDIT: Also, they should offer you a warranty on the work that they do this time around, independent of the existing warranty. Maybe only 30 days or so, but they should give you something for sure.

 

[TheWoodCrafter]

Re: 175 OS Glazed cylinder and low compression.

Bummer Deon.
I guess you now know most salesman lie.
I do disagree with Craig's quote below. This would be extending the warranty.
I don't think they will do that. Your warranty will end during the repair and they don't have to extend it. You are not paying for the repair so you don't get any extension.

EDIT: Also, they should offer you a warranty on the work that they do this time around, independent of the existing warranty. Maybe only 30 days or so, but they should give you something for sure.

 

[DeonCarpenter]

Re: 175 OS Glazed cylinder and low compression.

I talked with the dealer and mechanic again today; their seems to be some internal conflict there between management and their only mechanic. The warranty just says ?90 day warranty on motor? that is really broad and has none of the normal loopholes that a warranty normally would have. When I pick it up I may drive it directly to the Mercury dealer for a complete checkup. I don?t think you can tell a good job from a bad job from the outside. I am certain they are not going to extend the warranty.

What should the compression be fresh from the shop?
1998 Mercury 175 Carb.

 

[j_martin]

Re: 175 OS Glazed cylinder and low compression.

I would put them on notice, as nicely as possible, that you paid good money to have an engine refreshed, you expect a refreshed engine with no obvious weak parts, and you intend to get it by whatever means is neccessary.

Then have their work checked by a certified mechanic, taking good notes and pictures.

hope it helps
John