1984 Mercrusier 140 Help

[Dave Neptune]

j, pull the distributor cap and give the rotor a twist. It should move abot 15 degrees smoothly and spring back nicely. If not it needs a lube and possibly a cleaning.

Next double check for spark plug wire firing order just to be sure.

The timing should be checked at idle speed in or out of gear doesn't matter as it just needs to be set at idle speed. And by revving the engine you can confirm the centrifugal advance is functioning.

RE the carb, with a fuel bowl full look down the throat of the carb and give the throttle (engine not running) a twist. When you do you should see a small squirt of gas. This will confirm the acceleration pump.

One other possibility is carbon tracks in the dist cap. These tracks can be seen with careful inspection and tracks could cause this very problem. The tracks will offer a path of less resistance (due to compression) to the wrong cylinder.

Get back after these checks.

Dave Neptune

[lat 64]

Yea, I figured Dave would know this engie. I think they called it the "Iron Duke". Came in little Chevys. Merc mod was much bigger valves. I rebuilt one just around 1984! Nice engine really.

Sound was cool.

[joe_db]

Yea, I figured Dave would know this engie. I think they called it the "Iron Duke". Came in little Chevys. Merc mod was much bigger valves. I rebuilt one just around 1984! Nice engine really.

Sound was cool.

Hate to be a downer but not in my experience. The first one cracked the head just before the warranty expired. The dealer said we overstressed it, he sure hoped we didn't try pulling any waterskiers . We bought the boat specifically fore that purpose The second one made it past warranty before it died from continued water ingestion from a bad gasket. By the 600 hour mark we were on the THIRD one Don't know how long #3 would have made it, the boat sank soon after.

[lat 64]

Not a downer at all. Its a forum for this kind of thing. My experience was only one engine. Good to hear your story. Er, I mean sorry to hear it.
Its just like a dealer to say something like "overstressed".Thats a nothing term for diagnosis. If it can't pull a skier, it just won't pull a skier!
Seems to me there was chronic lack of cooling in the setup. Chevy engines like to crack heads and warp from overheating. But then, so do all engines. At the other end of the spectrum, I have friend that put a merc 140 into a landrover! He pulled a trailer from N. Carolina to Alaska With it.it takes all kinds.

R.

[Dave Neptune]

The Iron Duke

Lat, ah the venerable Iron Duke. The 4 banger was a great fishing/recreation applications. They would go for many hours with minimal maintenance.

Joe, I had a few friends with 16 foot skiboats using the 4 banger and it just worked them to a quick death. Pulling a skier was a big load for the Duke. The same boats with an IO and the 6 cylinder ran forever.

When working in boat shops we always tried to get the buyers to go for the 6 or a big OB,, they worked better and lasted far longer.

Dave Neptune

[joe_db]

Lat, ah the venerable Iron Duke. The 4 banger was a great fishing/recreation applications. They would go for many hours with minimal maintenance.

Joe, I had a few friends with 16 foot skiboats using the 4 banger and it just worked them to a quick death. Pulling a skier was a big load for the Duke. The same boats with an IO and the 6 cylinder ran forever.

When working in boat shops we always tried to get the buyers to go for the 6 or a big OB,, they worked better and lasted far longer.

Dave Neptune

Our poor runabout got used VASTLY beyond the design brief for a cheap boat to be used in a freshwater lake in calm weather. Besides for waterskiing and tube towing, it ended up doing a few multi-day trips and one memorable long trip at night into seas steep enough that going downhill all you could see through the windshield was green water lit up by the running lights
A friend of mine who happened to work for the company that insured the boat borrowed it one day. The next day I went to use it and found only the bow above water. THAT claim was paid fast with no investigation

[jlobdell12@gmail.com]

So if I was to get a V6 what kind of mods would have to be made. Will the out drive fit to the V6?

[lat 64]

Since there are so many special additions to a auto engine used in a boat, it seems like a good start to get a whole setup surplussed from a repower and go through it and restore it instead of buying all the bits to marinize an auto engine.
You may still have to buy many parts that will be worn or bad on the surplus engine along with a rebuild, but the setup will be a model for what you will want to end up with. A physical parts list if you will.

[Dave Neptune]

Pretty much all old "Chevy" engines use the same bell housing pattern so that should be no biggie.

The same holds true for many of the motor mounts as far as spacing, again probably no biggie.

Then you will need all of the adaptations Russ mentioned to make it work, not real easy.

Best look for a Mercruiser 6 out there somewhere. There are many as there are many who have also moved up to the V-8's.

Might be easier to sell & buy up too.

Dave Neptune

[ndutton]

Many years ago I knew a guy who did rebuilds for Mercruiser, primarily 350's. He and I were chatting about it and I asked if all he was doing was marinizing the base automotive engine (that's what it looked like to me) and he said oh no. The alloys of the crank, cam, rods, and gears (maybe more, I can't remember exactly) were completely different to withstand the loads applied with long continuous runs at constant RPM's.

[jlobdell12@gmail.com]

Lat, ah the venerable Iron Duke. The 4 banger was a great fishing/recreation applications. They would go for many hours with minimal maintenance.

Joe, I had a few friends with 16 foot skiboats using the 4 banger and it just worked them to a quick death. Pulling a skier was a big load for the Duke. The same boats with an IO and the 6 cylinder ran forever.

When working in boat shops we always tried to get the buyers to go for the 6 or a big OB,, they worked better and lasted far longer.

Dave Neptune

Hey Dave will the Mercrusier 6 cylinder fit the mounts and the out drive? Or will I need to replace out drive as well?

[joe_db]

My guess is the bell housing will be the same but the mount points might not be.

[jlobdell12@gmail.com]

I feel like a Dumb A_ _ !!!!

So after everything we have discussed in this thread I have to say I feel really stupid....As it turns out I have the 3.7 470 not the 3.0 140??? Why I thought it was a 3.0????I don't have an answer for that one. So all the issues remain the same but it is a 3.7 not the 3.0, all I can say is wow on my part. But with that said I have done a few things here and there as I get time but here is where I'm at now. I think we have determined the water leak is at the weep hole in the water pump/timing chain housing due to the failed lip seal, but while trying to determine this I lost fire, replaced the points and condenser but not the ignition coil. I did a OHM test on the coil and I think it is bad (again) this will be the 3rd one without even running it for long periods of time. Not sure what causes them to burn up so fast. I'm thinking that the lost compression on #1 may be due to a valve stuck open but I have not got to that just yet. I So once I get the coil replaced and get the water leak fixed I will move on the the compression issue, fingers crossed it is a valve stuck. I have no evidence of water in the cylinder or the oil so not sure where else to look. I will update again once I get repairs done.

[jlobdell12@gmail.com]

Found The Water

So I pulled the carburetor yesterday and low and behold the intake was full of water.... So the question is how did it get there? And what do I do at this point? Any ideas?

[joe_db]

Mercruisers are pretty well known for blown gaskets. I would do a compression check and do the A4 style leakdown test on the block and manifold. Meanwhile are you doing a lot of ignition-on testing and blowing coils? If this engine is old enough to be points-and-condenser, all the A4 coil issues apply and a Moyer coil wouldn't be a bad choice.