Logo
FULL SITE MENU

Removing 140 io wdropped valve

B

boo_radley

New member
"I had a mechanical failure wi

"I had a mechanical failure with my 140 and ended up with an exhaust valve driven sideways through the piston.
I'm wondering if I might possibly be able to remove the oil pan w/o pulling the engine.If I do pull the engine,do I have to drop the lower unit or can I just slide the coupler off the spline by moving the engine forward?
Any help is appreciated and I wonder what causes the head to come off the valve stem like that."
 
First of all the engine needs

First of all the engine needs to come out. Second you could remove the engine without taking the drive off but it will save no time. The drive MUST be removed so the engine can be aligned after it is installed.
As for the dropped valve either the stem retainer came out or the stem broke. In either case I'd think the engine was running at to high a rpm.
 
"Thanks Charli,I sort of figur

"Thanks Charli,I sort of figured as much.I guess I need to invest in a service manuel.Resources are very limited right now.
Do you know if the spline just slides right out of the coupler?I know about aligning it.
I was wide open when it failed but engine tops out at 3200.The valve broke off the stem and the stem is bent.It put a couple marks on the cylinder walls and flattened my spark plug.It could have been worse.
Thanks for the input!"
 
The correct manuals are just a

The correct manuals are just as essential as good tools. Buy oem manuals (mercruiser). the sterndrive shaft should slide right out of the splines on the coupler.

Do yourself a favor and snatch the engine out of the boat. It's not a bad job.
 
"Ed,
As for the shaft sliding

"Ed,
As for the shaft sliding out it could come right out or it could be stuck.
A lot has to do with how the drive was serviced and if you have enough room to move the engine forward so that the coupler will clear the shaft.

If the shaft was greased as needed it should slide out. On the other hand if the shaft wasn't serviced for a long time you may have trouble removing the engine. But you will have trouble removing the drive if this is the case. Anyway it only take ten minutes to remove the drive so why not just get it out of the way.

The rpm you were at is low for that engine so there could have been a problem before the valve came apart. Like the engine was not running on all the cylinders. Did this engine ever run at a higher rpm with the prop you now have?

Did the valve show signs that it was burned before it failed and what do the rest of the valves look like?
The big thing is to find out just what happened so it doesn't happen again. Check the best you can for the position of the timing and look for any sign that there was a vacuum leak etc.
Valves do not just come apart for no reason.

Depending on how bad the mark in the cylinder is you may need to start looking for a new block. You can't just smooth the ding over it must be removed if the engine is going to last.
It would be a good idea to check just how much the cylinder will need to be bored to clean up the damage. If it is a lot then the other cylinders will need to be bored to match. Just replacing one piston is not a good idea. If the engine has a lot of hours on it the rod and main bearings will need replaced. Removing and reinstalling the same bearings on a engine with a lot of time on it doesn't work very well to say the least. Since the piston has been damaged from hitting the valve at the top of the cylinder it's safe to say the rod is bent as well. What may look ok to the eye could be damaged / bent. The head could be cracked as well.
So as I see it you need at the least a valve,the valve spring & keeper,the valve seat replaced (which means the head must be taken apart)a rod and piston with rings,a gasket set,rod bearing, machine work on the cylinder(which means the engine must be taken apart).

It could be better and cheaper in the long run to find another engine and trade the one you have in as a core or find a used engine. By the time you get done patching the engine you'll have almost same amount in parts as a rebuilt engine. If it goes out in the first few hours you're out all that cost plus the time for doing all the work.


I know that parts or another engine are not cheap but just replacing the piston without doing the work needed is in my opinion a waste of time and money.

Unless you live where it is warm all year the season is just about over anyway so why not save up over the winter and do the repair right.

This will give you time for finding a deal on parts or another engine. I have no idea how much an engine kit for that is but it can't be a whole lot. Then you just have the machine work which also shouldn't be that much and the cost of the rod and valve parts. I'd think you can have a rebuilt engine for around $700 if you do all the work except the machine work. Then again I could be way off on the cost and that's if the rest of the valves, the head and block are ok.(block may have damage you can't see)
I would explore all options before you do anything.

Best of luck and have a safe winter."
 
"I am assuming it reads correc

"I am assuming it reads correctly,it has always worked for all the years I have owned it and reads around 3200 or just over at max."
 
Ed;
Something doesn't add

Ed;
Something doesn't add up. You should be getting more like 4200-4400 RPM at WOT; 3200 sounds way low. Is there some reason you have the boat over-propped? Does it take a long time to plane out? What length and weight is the boat?
Rod
 
"Thanks for the interest and c

"Thanks for the interest and comments.
The boat is an 18 ft bowrider,an 84 fiberglass deep V.Not sure of the weight but it's an older heavier model.
It planes out just fine and runs 42 MPH or slightly higher with a tail wind..It sounds like it's wound out pretty good on top end and I always thought that the RPM's seemed low but it's my first boat so I really didn't know.Could be that the tach has a problem but other than that it ran pretty darn good I thought.
It shows less than 500 hrs and had 190 hrs on it when I got it,so I've driven it quite a bit.Could be the hour gauge was unhooked by the previous owner so you really never know the real hours.
Later this week I may get some help and try and drop that lower unit.It looks like it has 6 horizontal bolts securing it.I've done mechanic work on cars and motorcycles but this is my first boat so I'm unfamiliar with these lower units but everything else is pretty simple on it so I'm hoping it won't be a problem."
 
"Ed;
I ran a check using your

"Ed;
I ran a check using your data, and to turn 42 MPH @ 3200 RPM, you would have to be running a 30" pitch prop, assuming a 1.98:1 drive ratio and about 10% slip, which is common for light boats.
Since I doubt you are running a 30" pitch prop, your tach must be wonky.
If you are running say a 19" pitch prop, your actual RPM is more like 5100, which is over limit, and likely accounts for why she has dropped a valve, just as charli said earlier.
You need to get the tach checked/replaced, and spend the money and get yourself a manual before you start.
What pitch is your prop, and is your drive a 1.98:1 (should be stamped on the top of the housing)?
Good luck,
Rod"
 
"Ed;
Glad to help.
I had ano

"Ed;
Glad to help.
I had another thought; is it possible that your boat once had an inline six? I am assuming it is now an inline four, but at one time the 140 hp used an inline six.
If so, then the tach is set to see ignition pulses for a six, and now it is only seeing pulses for a four. This means it will read 2/3 of the actual RPM; in other words when you are reading 3200, you are actually turning 4800 RPM.
Some tachs have a setting screw on the back to adjust for 4, 6, or 8 cylinder. If so, it is an easy fix. Otherwise I think you will need a new tach.
Good luck,
Rod"
 
Back
Top