Confused with 5.7L Timing Cover Replacement

[ColonelNivlag]

Hi all,

Relatively new to this boating business. The wife bought me an old Mastercraft Stars & Stripes for my birthday last year. It was purchased for relatively little money, to see if we'd enjoy boating, and could make it work as a family. The boat was *relatively* faultless last year. A few minor niggles & comedy moments but safe to say we got the bug!

Anyway, one of the niggles was a smallish oil leak. Which I contained throughout the summer with absorbent pads & I vowed to sort before the next season.

So here we are...

I'm not 100% on the engine I have, but I know the boat is an 80s model. 89 I think. I believe the engine is a Mercruiser 260 5.7 V8.

So, I located the oil leak, pretty confident it's the timing cover. I ordered a new one + gasket, for the above engine.

Next job, Belts off, pulley off, balancer off, all good.....

except, the timing cover is plastic! Not metal like the one I ordered. This surprised me, as the engine is surely too old for the plastic cover? Perhaps someone has already done this before? Or the engine has been rebuilt?

Anyway, I popped the cover off and started looking at using the metal one instead. However, slight problem, the cover wouldn't fit! On the crankshaft, there's a reluctor ring, for the crankshaft sensor? I assume? Which in itself is interesting... as my boat doesn't have anything connected to the sensor!

So by this point I'm totally confused and not sure how to proceed. I was worried the metal cover is somehow wrong for my engine, so I ordered the same plastic cover as is currently on. It was working OK after all.

So, all good. Except... the new cover has arrived today, and there's no gasket with it? The new cover does have a factory fitted grey rubber / gasket / bead around the edge but should there not be a gasket also? The old cover had a pretty heavy duty rubber gasket on too, but I can't seem to find one online (I'm UK). Is this needed?

In summary:

1) Should I remove reluctor and go with metal cover and paper gasket with silicone?
2) Should I go with plastic cover and no gasket. Do I use Silicone still?

Hopefully some pictures attached. (It's an old boat, so go easy, she's part of the family now)

Help appreciated.

 

[Bondo]

Ayuh,..... Welcome Aboard,...... The hull might be an '89, but the motor has been replaced, with a newer one,.....

Post up the serial number from the tag in yer last picture,....

 

[ColonelNivlag]

Ayuh,..... Welcome Aboard,...... The hull might be an '89, but the motor has been replaced, with a newer one,.....

Post up the serial number from the tag in yer last picture,....

Thanks!

Post it here? It's: K163789

 

[Bt Doctur]

serial number says bolts and grommets so I`d say plastic housing number says 1997efi 90-80950095

 

[nola mike]

Looks carbed (?) with v belts, so everything swapped over from the old motor likely. AD, was there a CPS on the 97 EFI? You'd want the composite cover, maybe post pics of the gasket difference. Also wondering if you have vortec heads, which would be another upgrade. Also, what are those loose hoses near the carb?

 

[Scott06]

You have a 96 and up vortec block, which is actually better… you can see 8 vertical intake bolts and the plastic cover plus electric fuel pump… just order parts for 96 and up the plastic cover is technically not reusable …

 

[dubs283]

Should I go with plastic cover and no gasket. Do I use Silicone still?

Yes, and yes

And you should replace the oil pan gasket. It has now been compromised by removing the timing cover and will most likely not resolve your oil leak. The issue is on GM small blocks you must use RTV or similar in the corners of the oil pan gasket. Seeing as how there was a leak there, whoever installed the oil pan gasket/timing cover did not do it correctly.

The timing cover goes on first, then the oil pan. Not worth trying to accomplish what you are, may as well pull the motor and do the job the right way

 

[Scott Danforth]

get an aftermarket aluminum timing cover (just google aluminum timing cover vortec) and skip the leak prone plastic part.

Holley makes one, Summit makes one, they are all cheaper than the plastic part

here is one

Holley 21-150 Holley Cast Aluminum Timing Covers | Summit Racing

Free Shipping - Holley Cast Aluminum Timing Covers with qualifying orders of $109. Shop Timing Covers at Summit Racing.

www.summitracing.com

Motor is a 1996 or later motor that was swapped in, running the old accessories.

you will need to keep the reluctor as it is spacing out the damper, or you need to address accessories to keep the belts aligned.

 

[76SeaRay]

What Scott said. I do believe they make one with the sensor hole and one without it. The sensor is a potential leak point. So, I think you have a choice there.

 

[ColonelNivlag]

Thanks all, I've attached pictures of the old gasket and the new cover I've already purchased. You can see the grey beading on the new cover. This is all I need? With some additional RTV?

I'm thinking the gasket previously installed is for the aluminium cover and thus was incorrectly fit here? Do you agree?

I'll consider an Alu cover instead as well as the advice on pulling the motor to do it properly. Appreciated.

 

[achris]

The aluminium cover was never a GM option. It's EXTREMELY unlikely it has previously had an ali cover. Likely is leaked before and the PO through it a good idea to put an additional gasket ( it wasn't)... I have much experience with leaking timing covers...

Chris...

 

[Scott Danforth]

The aluminium cover was never a GM option.

Correct, GM thought plastic was a good idea. the aftermarket racing world came up with the aluminum parts