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SubTopic :: Dismantling transom shield part
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Jay Berkowitz
posted 08-25-2008 5:08 PM

I have a 1977 Chris Craft Lancer with a 1977 280 outdrive mated to a SBC. I am in the process of dismantling the outdrive, and pulling the engine. Since I am having great trouble unbolting the intermediate housing (a Chris Craft part – a 6” cylindrical extension) - from the bell housing, I have decided to unbolt it from the transom housing. I have removed the outdrive. There are six bolts, 3 small arcs of metal with ends bent (to keep the bolts from turning) for each 2 bolts. These hold a ring with a gasket behind it. One of the 6 has sheared off half way down it's length. The bolts thread into the intermediate housing which in turn bolts to the bell housing. Any suggestions on how to pry the ring out, as it has been in place for 31 years? Once removed, I assume I will be able to pull the engine as the front engine mounts are removed. Once everything is apart, I will bring the intermediate housing to a machine shop to remove the sheared off bolt. Thanks. Jay

Robert Fierro
posted 08-25-2008 6:23 PM

Strictly speaking, you don't have to removed that ring if all the bolts are out/broken off. Wiggle the intermediate housing up/down, side to side from he inside. That should break the "seal". That ring compresses a thick rubber donut that acts as a seal and also keeps the intermediate housing "clamped" to the transom shield.

Robert Fierro
posted 08-25-2008 6:28 PM

Also while you have it out, have the bearings replaced. Some folks recommend using bearings that only have a seal on one side ... depending on the version of that housing there are fittings top and bottom for grease. The bottom one (usually a pipe plug) should bereplaced with a "Zerk" fitting. Annually you should REMOVE the top plug, and use a grease gun to inject grease until som ecomes out the top. Replace plug. If you forget to remove the top fitting you could damage the seals on the bearings. Some mechanics just replace the bearings with "permanently lubed" bearings.

Jay Berkowitz
posted 08-25-2008 8:49 PM

Thanks Robert. As far as "wiggling" the intermediate housing - I am going to have to wiggle the whole motor as the nuts holding the intermediate housing to the bell housing are frozen solid. I have had no success with any type of socket - standard, metric, 6 point - the damn nuts seem to be tapered! VERY frustrating. That is why I went to the transom housing instead. I will keep you informed. Thanks, Jay

Robert Fierro
posted 08-26-2008 8:00 AM

Based on my "extensive" personal experience (once) swapping engines in a Lancer, I found that having the engine attached to the intermediate housing ended up easier than disconnecting the engine when it came time to put it back together. As you stand now, just unscrew the engine mounts from the stringers (there is a metal plate buried in the fiberglass) and move the engine side to side slightly (a 2x4 between the manifolds and deck will work well). I don't know about the exact internals/deck structure on your year Lancer, but on mine, I had to remove a short transverse "stringer" ( actualy just the deck support, not hull) that was in front of the engine (aft of the tank) in order to get the engine to come forward enough to come out. Its VERY tight. Screws (at least on mine) for that deck support are underneath the transverse support and upwards into the fore/aft support at an angle. You want to take this out first (if your boat is built that way) BEFORE you try to remove the engine. Engine will need to come forward a good 6 to 8 inches (as I recall) to come out. Don't even think about reusing the rubber donut transom seals.

Since much of this is aluminum, before outting it back together, buy taps a die sets for all bolt sizes (blind or blunt end taps) and "chase" all the treads, i.e. after brushing the bolts, use the die to clean the threads and use the tap to clean out the threaded holes. Repair any badly damaged threaded holes with a "HeliCoil" insert. I'd buy new nuts and bolts for the engine/housing flange.

Rick E. RicardoMarine V/P
posted 08-26-2008 11:29 AM

I'll post more on this later this evening if that will help......
There is an easy method for continuing without much trouble.

For now:
Use extreme caution if you are going to run a thread tap into any of the AQ series Volvo Penta "thread inserts". These Thread Inserts (yes, very similar to a "HeliCoil" and are in all V/P threaded holes), are a type of SS material...... and you DO NOT want a sharp tap trying to clean or remove any burrs from this material.

If you must, run a greased Grade #8 bolt of same size/pitch gently into each hole and only after blowing each out with compressed air.

Quickly here.... go ahead and remove the remaining bolts. Drill and split the "Clamping Collar" as to get it out of your way.... (these are a dime a dozen).
The "Flywheel Cover" (bell housing in the auto world) will come forward and out with some force.
If the engine has been unbolted from the flywheel cover, you have the opportunity to heat all six bolt bosses inside of it. This helps expand the aluminum and break up any corrosion!

Often only one Rubber Sealing Ring needs to be new.... the inside one.
This one does the actual sealing of the Flywheel Cover/Transom Shield.

Shoot me an email if you wish.... be glad to further explain if need be.


Rick E. RicardoMarine V/P
posted 08-26-2008 12:29 PM

Jay, I think what you are describing are the rusted hex heads of the six 3/8" clamping collar bolts (9/16" heads).
These are galvanized steel, and the galvanizing has worn away and the heads are disappearing.
I've had to on several occasions had to drill the heads from the bolts. Then you drill a series of hole accross two places on the clamping collar. Then you split the collar with tool of your choice allowing it to come off.

These are a special "Tap" bolt threaded almost the entire length of the bolt. A Volvo Penta item unless you special order via a "Screw Thread" company.

Rick E. RicardoMarine V/P
posted 08-26-2008 12:38 PM

Just a friendly FYI for all in this thread:
The part bolted to the transom is a "Shield" or "Transom Shield" in v/p terms.
The bell housing is a "Flywheel Cover" in Volvo Penta and most other marine terms.
W/ a two pc flywheel Cover and housing.... the housing is called a "Primary Drive Shaft" housing.... and will use the Borg Warner bolt pattern...... and are occasionally not by Volvo Penta.... Holman Moody and others made these as well.
The shaft that needs to have new bearings/seals installed is a "Primary Drive Shaft" in v/p marine terms.
The engine coupler will often use what is called the Borg Warner drive coupler "spline".... very common.
These bearings will need to be OPEN bearings so that future lubrication can enter the bearing. Not a sealed bearing! Either is available in the same bearing!
The part number has an extension on it for a sealed bearing.... the seals can be picked out with a knife if need be.

Any of these bearings and seals can be purchased from a major bearing supplier saving you some $$$.

Now........., before you do the bearings, you can add an eighteen inch grease gun extension hose ($7 at auto parts store) (and w/ a Zerk at one end of the hose) into the Flywheel Cover (tap the hole by running 1/8" TP tap into the hole....no need to drill it) and no SS insert in this area, BTW.

Use a good high pressure grease.... not green or blue marine grease! Ya want the good stuff in there!
Rotate the shaft as you pre-fill the cavity before you install the seals and only when you see new grease coming through!

If you will fasten this hose to your throttle cable or ????, you'll have a remote grease fitting location that won't be forgotten like is has for the last 30 years.

Every 30/40 hours or so, lube this w/ the engine at idle.

I do not want to sound like a know/it/all, but thought I'd share this with those who have these drives.
It just may gain you a day on the water and out of the repair shop!


Jay Berkowitz
posted 08-26-2008 5:11 PM

Thank you all for your suggestions and wisdom. I will keep you all updated.

Jay Berkowitz
posted 08-26-2008 8:21 PM

I can't get the picture to appear, so here is the link to a pix of the primary driveshaft housing


Jay Berkowitz
posted 08-26-2008 8:33 PM

Rick E. RicardoMarine V/P
posted 08-26-2008 10:28 PM

Yep, several companies made these Primary Drive Shaft housings to fit the Volvo Penta drives..... most of the time moving the engine forward by a few inches!
These use the Borg Warner bolt pattern and Borg Warner drive coupler splines. Quite common in the 70's.

The bolts that attach this to the Flywheel Cover often use a keeper on the rear side. The nuts/bolts were often regular steel and would rust up. Looks like you got that apart though.

Robert Fierro
posted 08-27-2008 7:54 AM

I noticed from your picture that it appears as if there is a blocking plate installed on the exhaust port to the transom shield? IFSO, I'm interested in how your exhaust exits the transom. I've determined that I'll have to convert my boat to thru transom exhaust since the exhaust port thru the transom shield is waaaay undersized per the engine manufacturer's specs for my new engine, a 260HP 5.7L FWC MERC, (and I'm not getting the WOT that I think I should get with my prop)

Rick E. RicardoMarine V/P
posted 08-27-2008 9:05 AM

Robert, does your exhaust bellows have the flapper inside of it?
If so, I'd remove it!
I don't care to see the bellows flapper on any of the V-8's.

Not sure which drive you have....... but the 280 offered a production model only flapper! You can not buy this flapper over the counter!
If you do not have one on the lower unit outlet, you can retro fit a flapper from the 290 drive.
This part is available.
It requires that you remove (grind down) the little center protrusion in the casting.
Easy to do and it will relieve some exhaust restriction! IMO.
If you have the 275, 290 or the DP, it's moot! Ya got one on the drive, right?


Robert Fierro
posted 08-27-2008 1:44 PM

I now have a 280B drive. It was a 250D drive with the wrong ratio previously (what a pain!) Drive used to have a flap on the exhaust port but its long gone. The drive (used of course) came with flappers in the bellows. I wasn't happy with them at all when I looked at them, but could not find a new flapper for the exhaust port. My concern is that the I.D. of the Y pipe at the point that it transits the transom shield is about 2 -1/2 inches. Specs for engine say: Minimum exhaust 3" for duals and 4" for single exhaust. 2-1/2" a looong way from 4. Of course having the flaps in the bellows makes things even worse. My last 1969 23 ft Lancer with a 250B drive swung a 14 1/2x 21 prop at 4200 rpm with a 240 HP 318 Chrysler in front of it with 2, 3" thru transom exhaust ports w/mufflers. Now my 260 HP 350 CID Merc will only turn a 15x21 prop at 3800 rpms thru a 280B leg. Drive ratios verified as 1.6:1 in both cases. Did not realize I had this problem last year as the tach was funky. If I can't get to the whole thru transom project (with mufflers, per NJ law) this winter or next spring, I'll swap the bellows and put a 290 flap on the drive. Thanks for the tip.

Rick E. RicardoMarine V/P
posted 08-27-2008 1:52 PM

Robert, Volvo has not changed this port size in all of the years this drive style was being made.
I have them on my twin 280 HP 5.7's and they don't seem to complain.

Your TAT may be something to check on this engine.

BTW, the "B" designation on your drive transmission only pertains to the original configuration of Transmission/Intermediate/Lower unit gear ratio....... of which you are correct, it would have been the 1.61:1 over-all ratio.

However, you will commonly see either a C, D or B transmission on any of the lower units (whereby an owner has replaced an upper) since all transmissions are of the same gear ratio..... Just an FYI on that for you.
(insert Smilie here) Can you use the emoticons on this site?

Robert Fierro
posted 08-27-2008 6:56 PM

The "original-to-me" 250D drive on this boat was tagged 250B. The current 280B drive is a "B" ratio... I checked b4 I handed over any cash :-) Re: TAT...It should be OK as the engine is a brand new (late 2006) factory fresh Mercruiser (MIE 5.7L) with a total of 22 hrs on it. I have a copy of the factory manual, I'll look up the procedure. Jay...sorry we hijacked your thread...:-)

Rick E. RicardoMarine V/P
posted 08-27-2008 7:59 PM

Well, ya got me, Robert!
Other than suggesting that I don't believe that this is your exhaust port size at the shield causing this!

Ignition TA will hold back performance if all else is OK. Key Word being ALL ELSE!
It may be worth putting a light on her and seeing what she's doing @ 3k rpm or so.

Are you by chance using one of those silly M/C TB ignition systems? LOL
Those are nothing more than a marketing strategy for captive and proprietary parts sales..... Nothing more! Sheesh.
Well, No hard feelings if you do, OK? LOL

The one good aspect is the knock sensing control portion of the later systems.

I'm really a M/C guy in Volvo Penta clothing! Ouuooooowhhhhh!

Robert Fierro
posted 08-28-2008 7:52 AM

Its a factory stock engine, the only option was FWC, so I guess I do have the TB system. There is something funky going on as per my estimates, this engine should spin that prop at about 4400-4500 RPM. But checking TAT is a simple test...If only I hadn't given my timing light to my son who now lives in southern CA... (I'm in NJ)

Jay Berkowitz
posted 09-01-2008 8:30 PM

Hey guys. The pix is NOT of my transom shield. It someone else's. I included it so you could see what I have. I do have a flapper in the exhaust where it sits in the transom shield. I too, will need the 290 part to replace it. I should have looked for and inboard Lancer.....

Robert Fierro
posted 09-06-2008 11:07 AM


This is my second I/O Lancer. When I was looking around to buy the one I have now, I looked at a couple of inboard powered ones. In the end, I decided on another I/O powered one for a number of reasons: 1) Inboard powered Lancers have the prop in a pocket (at least the one I saw) and I don't like props in pockets as I feel that the prop is not as efficient as an I/O. In an I/O you can set the prop angle to parallel to the hull which is the most efficient. 2) I boat in a fairly shallow bay (Barnegat) and every once in a while... :-) I could avoid the shallow water issue totally, however, I use the boat for fishing as much as for anything else and the fish tend to stay away from the marked channels. 3) Every once in awhile, I like to be able to beach the boat, not an attractive scenario with an inboard. 4) If my prop gets damaged ( this has happened three times in all the years I've boated), I can change it at dockside as I carry a spare prop (a used not quite correct sized one, but one that works), without getting wet, or once, beached and wet to my knees. Yes, I/Os are a bit more maintenance than straight inboards, but all in all I feel that for my situation at least, worth it.

BTW, if you think V/P drives have problems, check out the Mercruiser forum :-0...

Jay Berkowitz
posted 09-06-2008 7:51 PM

Yeah, I also boat in some shallow waters. I had a 26' Penn Yan with a tunnel drive. Wandered all over at no-wake speed - most of the rudder was up in the tunnel, and no keel to speak of. Also no control when backing up. It is just that an I/O drive is yet another very complex piece of machinery subjected to salt water corrosion (in my case)on a i/o boat.(the motor of course,being the other one)

Robert Fierro
posted 09-06-2008 8:16 PM


Re: corrosion... On my first Lancer there was a band of rust and corrosion on the engine towards the rear (the previous owner of my "new" one always had a full cover on it and was it relatively rust free). It took me awhile to figure it out. On my Lancer at least, there is a bulkhead that sits up against the top of the hull aft that includes the "fish box". The engine "Box" butts up against and if you have a rear seat, the rear cushions as well. What I found was that water ran off the stern of the boat and into the gap between that bulkhead and teh rear of the boat. Also water ran off the seat and down between the seat bottom and the seat back onto the engine. On my new Lancer, I hopefully fixed the proglem for just a few dollars and half an hour of my time. Materials: 8 ft section of "J" channel (used when putting vinyl sideing on a house) Monel or SS staples, tube of boat life calk. Cut J channel so that it fits on the side of the bulkhead facing aft, centered over the engine and expending about 6 inches past the engine on either side. Use caulk on strip and staple J strip to bulkhead. On the other side of this bulkhead cut and attach a second piece of J channel in like manner so that it just fits inside the engine box side to side. "Rain Gutters" for the engine! Will take and post a picture if you are interested.

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