OMC 5 L Stalled and Stayed Stalled

[JDusza]

I am working on a friend's Four Winns with an OMC Cobra, 5 L, V-8.

I changed the spark plugs, distributor cap, rotor, engine oil and filter and lower unit oil. There is a blockage between the lower unit fill and check holes. Issue #1: Oil is not making it up through the unit. I ended up with about a pint in there. Issue #2: The exhaust boot is totally blown out, virtually non-existent.

We put the boat in the water and had to troubleshoot a couple minor issues; oil leaking from the new filter, required tightening; missed an ignition wire at a plug so performance was off for a while. with problems seemingly fixed, we took off. The boat ran very smooth with energy and speed. We tromped on it. It was a very good ride and indicated good things.

We ran the unit for about an hour both at high and low speed. We settled in with a low speed cruise. During the low speed cruise, the engine snorted and flat out quit. It did not restart and seemed to be binding for when the starter was engaged, the whole engine and outdrive would jump. The starter had all it could do to turn the crank. It felt as though someone had stuffed a rag into the ring gear.

We got it back to the dock and I pulled the spark plugs to eliminate compression. The engine turned over, tough at first, then gradually got easier and easier. After all this the battery was done, so I charged it and proceeded with a compression test, 152 to 155 across all 8, then re-installed the spark plugs and started it up. I was elated that it started for a couple hours before it wasn't going to even spin. I am very happy to have it running.

What would have caused the engine to quit and appear bound?

Wait, ... there's more... remember, while working on the boat I noticed the exhaust boot is totally dysfunctional. There basically isn't an exhaust boot any more. The exhaust boils at the transom. There is no exhaust going through the prop. Additionally, we find the boat taking on 4 to 5 gallons of water each night. We have decided to pull the boat and find the leak and evaluate the boots. It may be the boot, but I am not that familiar with the OMC to know for certain.

So, if we ask again, what cased the stall and binding, could it be water got sucked into the exhaust?

Anything else? I am stone cold stumped.

Thank you,
J

 

[Bondo]

Re: OMC 5 L Stalled and Stayed Stalled

#1: Oil is not making it up through the unit. I ended up with about a pint in there.

Ayuh,.... Are ya Sure it's a Motor problem,..??

A good part of the drive turns with the crankshaft....

 

[JDusza]

Re: OMC 5 L Stalled and Stayed Stalled

There is the rub... isn't it?

No, I am not sure it is an engine problem. Likewise, I thought the clean shifting more or less indicated no laundry stuck in the prop shaft. It took an awful lot to spin that engine with the transmission in neutral and spark plugs removed.

Now, I am sure there has been no maintenance on this rig for way too many years.... but, and you can endorse this, there is some lube in the lower housing; better than no oil at all. Granted, it should be taking more. It's a monster lower unit housing.

I hope to have it running on the muffs tomorrow. In order to replace the exhaust boot, do I need to pull the pivot housing from the gimbal assembly? For the drive shaft / u-joint boot you would, for you have to feed the drive shaft through the boot.

Thanks.
J

 

[bruceb58]

Re: OMC 5 L Stalled and Stayed Stalled

If you only put a pint of oil in the drive, my guess is you locked up your drive. How did you try to fill it?

What year is the drive? Most Cobras except the SX Cobras need to be filled from the center plug, not the bottom.

there is some lube in the lower housing; better than no oil at all.

Too bad you thought that. Your drive is probably locked up now. I would pull the drive and see if you can rotate the engine.

edit:remove older OMC Cobra fill description since the drive is an SX Cobra.

 

[JDusza]

Re: OMC 5 L Stalled and Stayed Stalled

I can spin the engine. The engine starts. I guess I need to look at the lower unit again. Thank you for the info.

When I drained the original lower unit oil, I got next to nothing out.

I did try to fill from the bottom and it felt like there was an obstruction. So, filling somewhere else makes sense.

I have to take a closer look at the unit for this dipstick. I am not familiar with OMC. I think my drain plug is on the port side. I could be mistaken.

Cheers!
J

 

[bruceb58]

Re: OMC 5 L Stalled and Stayed Stalled

The dipstick is on the top and if you tried to fill it through the bottom without removing any plugs, it will be next to impossible to get any oil in because of the pressure working against you. When you drain it you want to take all 3 plugs out or it won't drain properly either.

Do you know what approximate year this is?

Before you run this again, and that includes in neutral in the driveway, fill the drive properly.

 

[JDusza]

Re: OMC 5 L Stalled and Stayed Stalled

Thanks. That is exactly what I am going to be doing. All the symptoms are falling together to say I just don't know these parts. I did not drain and refill this properly.

I was just at the boat. I took a pant-load of pics and am on the drawings right now. I will be re-performing the drain / refill procedure; the right way! I also put the plug back in and filled the bilge so I can look for a leak in the stern area; wondering if that bad exhaust boot is letting water into the bilge.....

1994, model is 502ACPMDA.

There appear to be four "holes" into the lower unit; dip stick, drain hole at port bottom, fill plug on port side about mid-way up gear housing and plug hole on stern side of gear housing. A couple of these will need coaxing to open.

Next, is the exhaust boot. What should I expect if I run without the boot intact? Will water get sucked up into the exhaust pipe and stall it? Does cooling water have to exit the prop? And, I suppose another question is can I replace the boot without separating the housings? I know..... lol....

Thank you, BruceB and Cheers!
J

 

[bruceb58]

Re: OMC 5 L Stalled and Stayed Stalled

So your model drive is a Cobra SX version so you do fill at the bottom after all so you need to ignore my previous post and I will edit it to remove the picture.

Remove the dipstick at the top of the drive.

Remove the back cover held on with 3 10mm screws. Inside there is a plug that you need to remove. This is the level plug.

Remove the bottom drain plug and allow the drive to drain.

When filling, pump the oil in the bottom hole until oil comes out the level hole that is behind the rear cover. While holding the pump in the bottom hole, replace the level plug and the dipstick. This will keep the oil from running out when you pull off the fill hose. Replace the bottom plug and then check the level again on the dipstick.

The extra plugs you see on the side are holdovers from the older design that were drains for water cavities. You don't need to remove these.

Just to be sure, remove that back cover and post a picture to make sure you have the SX drive. You should see the shift linkage underneath it.

By the way, it is good practice to always change the o-rings and gaskets on all these plugs when ever you change the oil.

For your other question, you can run without the bellows for what you are doing. When you are running on muffs, most of the water comes out the idle ports close to the transom.

 

[JDusza]

Re: OMC 5 L Stalled and Stayed Stalled

BruceB,

You nailed it! It is an SX drive with the level hole under the cover. The transmission linkage is right there.
I was able to get this cap plug out and redid the job with much better results. Took a nice long drink. I still cannot get the dip stick cap plug loose. I will have to fashion a wrench.
The port plug is a flush port.

So, I think I am ready to put it back in the water to try again. In the yard it starts, runs and shifts well. Also, sitting in the yard with water in the bilge, I find no obvious leak although I know it is taking on water at the dock.

Cheers!
J

 

[bruceb58]

Re: OMC 5 L Stalled and Stayed Stalled

Get the biggest screwdriver you own and put a vise grip on it or possibly use an impact driver.

You need to use GL-5 Synthetic in the drive. I use Mobil 1 75W-90 from the auto parts store.

Have you pulled the drive to see if there is water in the bellows? If you have torn u-joint bellows, that will allow water in the boat. Also, a rotten transom will let water in as well.

 

[JDusza]

Re: OMC 5 L Stalled and Stayed Stalled

I have not pulled the drive to see if there is water in the bellows. From the outside, the u-joint bellows appears good. As mentioned, the exhaust bellows is, well, ... gone. I have to believe that exhaust bellows was also junk last year. I am not looking forward to pulling the drive for this unit has not been serviced in "forever". I'll bet it is going to be a bugger to get apart.

Still in the driveway with no obvious leaks. I'll take another good look a the u-joint bellows. The water in the hull probably isn't reaching the u-joint bellows. I'll have to check. The transom is in good shape. I'll check outdrive sealing again.

The plan is to put the boat in the water tomorrow morning and test it at load.

 

[bruceb58]

Re: OMC 5 L Stalled and Stayed Stalled

I highly reccomend pulling the drive. You need to do that annually anyway. Out of curiosity, how did the oil look that you drained out of the drive the first time you drained it? Was it emulsified at all?

You can't see cracks in the u-joint bellows very well at all without pulling the drive. Trust me, you need to be doing this.

 

[JDusza]

Re: OMC 5 L Stalled and Stayed Stalled

Good news, bad news.

If there were any doubt about transmission performance, it was settled today.
I have indeed lost the drive gears, but, after a great ride. Forward is completely gone and reverse is grinding it's way out.

The morning started very well with early maneuvers, stress and strain. All went well and I ran it at high speed for about half an hour. It runs very smooth, with more power than it's shown in years. After about the half hour, everything just quit; made some "jumping" noises and took the engine down. Forward gear is gone and reverse is grinding itself up. There is no doubt that gears are destroyed.

I hear you advice on pulling the drive, but, now, it's mute. I would have seen the failures going on.

I also gave this thing a much better inspection and did find the u-joint boot is also ripped, at it's first coil. This can't be new. This thing has probably been leaking for the past two years.

So, I'll be taking the lower unit to the shop for a tear down and a little more maintenance than I had planned. Can you recommend a good vendor for gear sets?

Cheers!
J

 

[bruceb58]

Re: OMC 5 L Stalled and Stayed Stalled

This is why I was telling you to pull the drive first. You would have seen water in the bellows and not taken the boat out. You could have really saved yourself a lot of money here. You have big problems now.

Good luck. This is going to be very expensive. I would look for a used drive myself.

 

[JDusza]

Re: OMC 5 L Stalled and Stayed Stalled

I hear ya, but, I think the money was going to be spent anyway. The damage was done inside already.

A used unit, eh? Are the gears not available?
Where's the expense if I do the repair myself?

Thanks,
J

 

[bruceb58]

Re: OMC 5 L Stalled and Stayed Stalled

To rebuild the unit yourself is going to require a bunch of expensive Volvo specialty tools. Start looking for Volvo SX drives of the same gear ratio.