AQ225D/280 Engine/Transome mounting bolts

[Sector R]

I am working on a 1984ish Volvo Penta AQ255D with a 280 stern drive that needs new flywheel cover bearings and seals along with a rebuild of the universal joint.

I have not yet pulled the engine but I loosened all but one of the 6 mounting bolts that attach the flywheel cover to the transom shield. The heads of the bolts are all excessively rusted and corroded. One is so badly corroded that I probably will have to buy an extractor tool to remove it.

The "Connecting Components AQ Drive 280" parts guild lists this bolt as #41 Hexagon Screw 191844 that lists for $10.10. I have not been able to determine anything about the exact specifications of this part. I fully removed one of the bolts and noted that it appears to be a simple galvanized 3/8"x4" #8 bolt.

My question is this: Are these bolts supposed to be galvanized? I sort of expected them to be stainless steel, which would be more in line with the listed $10 price tag, but perhaps there are other reasons for them to be galvanized.

About 13 years ago, due to a freak trailer axle failure, we had to have the Transom shield replaced. I have no idea if they used the original bolts when that was done.

Thanks.

 

[Scott Danforth]

you will note that the thread length is custom. yes that is an original bolt.

standard thread length on a typical bolt is 1-1/4" that is about 2-1/4" as they need to draw the o-ring clamp in.

they are grade 8, originally I believe flurokoted.

they would not be stainless because they go into aluminum threads, and stainless does not have adequate strength.

your choice if you want to try stainless. you would have to get fully threaded bolts. dont try to cut threads deeper with a die, as cut threads weaken the bolt further than the original rolled threads.

 

[Sector R]

Thank you very much for responding.

While subsequently comparing the bolts to others I had on hand, I did note the custom thread length. I tested the fit of a standard 3/8" galvanized bolt and found the threads to be too tight to thread in by hand. I am now considering if I need to replace them all with the pricey OEM bolts or just the one that is not serviceable.

Thank you again for your help.

 

[alldodge]

standard 3/8" galvanized bolt

A galvanize bolt has different thread thickness then a standard bolt. The bolt has been coated with galvanize which makes is thicker

I'm unable to see the head clearly in the pic, but it does appear to have 6 marks on it, and if this is the case then like Scott said, its grade 8. Galvanized is at most grade 5

 

[Scott Danforth]

having just installed mine a few weeks ago..... I am intimately familiar

personally I would wire brush what you have, coat with permatex #3 and install. then coat the heads with permatex #3 and call it a day.

BTW, do a google search, the bolts are $6 from a few sources.

 

[Sector R]

Thanks again to those who wrote responses.

I have searched the net high and low and cannot find this particular part for any significant amount below $10 us. Shipping then becomes the only real issue. I think I will just order the one replacement bolt and hope I don't ever have to pull the engine again.

I often muse about the price of Volvo Penta parts, thinking they must all be made from precious metals. That said, I have had this boat for over 34 years and the engine and stern drive have been very reliable. I would not have had to rebuild the drive shaft and u-joint if I had done a better job of inspecting the bellows.

I do have one more question regarding pulling the engine. I was prepping to pull the engine and note that the exhaust boots are very tight and do not appear to be very easy to slide off of the exhaust risers. It would appear to me that it would be easier for both engine removal and installation to just remove the two exhaust risers. Anyone have any thoughts on this?

Thanks again.

 

[alldodge]

The boots over time get sort of glued to the elbows. Use a hose pic, screw driver or other tool to slide under the boots to break them free

 

[Scott Danforth]

When I google the screw, a few show up in the 8-9 range. My last purchase was about $6 each

some times the exhaust boots get melted and stuck to the paint. factory hose is only rated at 250F.

if you need to buy some, PM me prior. they are 95mm (3-3/4") not 4". I may have some 95mm 4-ply 95MM silicone 500F hose left over

 

[jerryjerry05]

I take the risers off along with the hose.
That way you can inspect the manifold and the risers for corrosion/blockage.

Reinstalling. 2pieces of 3/8(?) all thread about 8" screw in front and back.
Lot easier than holding the mani and trying to start a bolt.