Mystery Bolt, AQ125a in 87 Bayliner Capri

I bought an old 87 Bayliner Capri last fall. The engine would not start when I got it, had zero compression on num. 4 cyl. I pulled the Intake, exhaust and head. To my surprise it looked like a new engine inside, zero ring grove, no burnt valves or seats... the compression problem was a stuck valve. I cleaned it up and got the stuck valve working properly but didn't reassemble until a couple of weeks ago. I have a bolt left over that I can not find a place for. The bolt is about 3 3/4" long with a plastic sleeve that's about 2 3/4" long with a 10mm head. It's obviously been somewhere hot, probably around the exhaust manifold but I can't figure out where. Any help will be greatly appreciated.
The engine does start and run pretty good now, considering timing has been set by ear by a guy that's nearly deaf.

If is still running points use a dwell meter to set them at as close to 62 degrees as possible then set the timing at 6 degrees btdc.

It is still using points, I have to buy a dwell meter and timing light, haven't needed them in years. My main problem is where does that bolt go?

Forget the bolt. If it was not obvious as to where it belonged...... it may have been a left-over bolt from some other project.

Your NEW main problem will be from NOT correctly setting and checking the Ignition Advance with a real timing light.

These Volvo Penta OHC 4 banger ignition distributors are notorious for developing rust/corrosion at the flyweight cams and at flyweight return springs.

Make dang certain that the flyweight system is advancing the spark lead progressively (as per OEM specs)........ and that the system stops advancing at the OEM specified degrees and RPM!



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It hasneen my experience they allways give you at least two or three extra bolts. My question is where are the other ones hiding

Thanks for the replies! I will properly time and set the dwell before the rig ever hits the water, just haven't yet. I picked up a dwell meter this afternoon. Haven't gave up on finding my old timing light yet.
Rick, I've had the distributor out, what I can see looks pretty good but I have not disassembled it. For a thirty + year old rig the engine is amazingly clean.
Kim, I know exactly what you mean but this bolt definitely came from this engine on this tear down.
So far I have installed a new timing belt and tensioner, new marine grade starter, new impeller in fresh water pump (can't be a sea water pump, I'm well over 500 miles from any salt water), flushed the heat exchanger, replaced the fuel line, drained the fuel tank, put a kit in the carburetor removed, cleaned and lapped all valves.

thanks again for the help.

Its called a raw water pump fresh or salt. I believe you engine has the same distributor as my aq131 the book calls for 32-36 degrees btdc at 4200 rpm. Set the base timing at 6 degrees at 900 rpm and watch the spark advance as you increase rpm. The timing should advance nice and steady and stop around 4200. rpm and be between 32 and 36 degrees btdc. You should really do the max spark advance test on the water for two reasons. Spinning the prop at those speeds can damage it with no load on it. Running the engine without in being in gear can damage the upper gearbox because the oil pump in the gearbox is on the propshaft and oil does not circulate out of gear and the upper gearbox heats up real quick.

Look under the heat exchanger is that a mount bolt for bottom of it?

Thanks for the info! That will help when I find my timing light or break down and by another, whichever comes first. I've been thinking heat exchanger all the time but so far I have not found where the bolt goes. I'll look it over good tomorrow. Thanks again.

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Sticks said:

Thanks for the replies! I will properly time and set the dwell before the rig ever hits the water, just haven't yet.
Adjust the dwell angle before you adjust the ignition advance.
Reason: a change to the dwell angle (after BASE has been set) will change the advance!

You will set BASE advance, then you will increase RPM as you watch the advance increase up to the "Full-In" advance as per OEM specs.
This is the more important aspect of ignition timing!

I picked up a dwell meter this afternoon. Haven't gave up on finding my old timing light yet.

Rick, I've had the distributor out, what I can see looks pretty good but I have not disassembled it. For a thirty + year old rig the engine is amazingly clean.
You will want to look at the flyweight system and at the flyweight return springs.
Make sure that they are clean, lubricated and that they move freely.
Equally important.... make sure that the return springs bring the system back to BASE index.
Rust/Corrosion will play Hell with these parts..... especially if the little return springs have become compromised!

Kim, I know exactly what you mean but this bolt definitely came from this engine on this tear down.
Was the plastic tube on this bolt shank when you discovered it?
Are you certain that it was not just simply laying in the bilge?

So far I have installed a new timing belt and tensioner, new marine grade starter, new impeller in fresh water pump (can't be a sea water pump, I'm well over 500 miles from any salt water),
Whether operating in ocean, river or lake water, this pump is a "seawater pump"!

flushed the heat exchanger, replaced the fuel line, drained the fuel tank, put a kit in the carburetor removed, cleaned and lapped all valves.

thanks again for the help.

Click to expand...

I'm either too new to the forum to be allowed use of html coding or too new to know how to turn it on! So I'm resorting to the old school quote system below. Hope it's not to hard to follow. kimcrwbr1 said: "Spinning the prop at those speeds can damage it with no load on it" I have removed the prop but will do the fine tuning on the water as you suggest. RicardoMarine said: "You will want to look at the flyweight system and at the flyweight return springs. Make sure that they are clean, lubricated and that they move freely. Equally important.... make sure that the return springs bring the system back to BASE index. Rust/Corrosion will play Hell with these parts..... especially if the little return springs have become compromised!" Great info. I will go through the distributor and check all. RicardoMarine said: "Was the plastic tube on this bolt shank when you discovered it?" Yes the tube was on the bolt shank. I actually vaguely remember pulling the bolt when I disassembled last fall. I took pictures of several bolts, before and after removal but didn't think I'd forget that one! I'm really new at being old and forgetful! I also didn't think it would be almost six months before I reassembled. RicardoMarine said: "Whether operating in ocean, river or lake water, this pump is a 'seawater pump'" I do know it's a seawater pump, the fresh water bit was my poor attempt at humor. Well actually I thought it was sea water pump, you all must know I'm an in-lander by now! Edit: sorry guys, had no idea that my line feeds would be removed!

The weather finally broke and I was able to get back to work! We actually had snow and sleet Saturday, I've only seen snow in April once before around here. I pulled the distributor again, tore it down this time. The advance weights and springs look good and they spring back in place when pulled open. I've got the dwell at 61.8, probably as close to 62 as I'm going to get.
I gave up on finding my old timing light and bought a new one, now I can't find the timing mark on the crankshaft pulley! It looks like I'm going to have to put a new one on it but could use a little help. With number one piston at top of compression stroke the new mark should go at zero deg., correct?
I've found my mystery bolt in the heat exchanger exploded view. It's 41, 42, 43 and 44 at https://www.marinepartseurope.com/en/volvo-penta-explodedview-7742840-26-15777D.aspx
Looks like you were right about the bolt, thanks Kim.

I finally found where the mystery bolt goes on my engine. It supports the copper tube that goes from the seawater pump to the connector on the strainer housing. I believe it would of only been a mater of time before I had a serious over heating problem without this bolt.

I finally found the timing mark, very light scratch is probably a better description, on the crankshaft pulley. I had to put no. 1 cyl. on at TDC to find it. I've uploaded an image but I doubt you can see the timing scratch in the downsized picture. If anyone else has problems finding the timing mark if you put the notch in the pulley between 2 and 3 o'clock the mark should be close to zero degrees. You may need a magnifying glass to find it!

I now have it at 6 degrees before TDC at 900 rpm. I revved it to about 2k rpm and it did advance. I will give it a final check once I have it on the water.

Once again Thanks to all for your help.

I can't seem to find anywhere to mark this thread as solved. If a moderator takes a look at this and you have the power to do so please mark as solved.