aq125a crank not turning

geoffreyc1212

Recruit
Joined
Sep 2, 2013
Messages
5
This is my first post, and I'm looking for alittle wisdom before I tear into this old beast. I bought a 1981 capri with the aq125a. The boat sat un covered for 10 years before I got ahold of it. The engine was rebuilt (have papers), ran once and the starter puked out. Long story short the boat was in the middle of a divorce battle and I got a sweet deal!

I replaced the starter, cleaned out the carb, didn't touch the beautifully clean oil that was in it, and started cranking. After a day of cranking it fired right up! Stumbled a bit at first and ran like a champ after that.

My issue... on my first run (after considerable rainfall) I hit a washed out sand bar. Hints the boats name "$udden impact". Sucked some mud into the cooling system and it overheated. I didn't let it get to the point of popping the cap. Pulled out the handy trolling motor and headed back in.

Flushed the heat exchanger and went for my second run. Outside of a bit of stumbling and backfiring between idle and 1500 it ran out great.

Third run I got 5 miles out and got into some thick vegitation. I shut it down as soon as I noticed a load on the engine. It didn't start for about an hour after that. Didn't want to run unless it was wide open and refused to start unless it sat for some time. I assume the coil got too hot under load.

Fourth run it was out for 6 hours with no issues at all awesome fuel economy, good speed everything ran out great. I started noticing it wouldn't get over 20 mph and the bow was getting pretty high. Opened the engine cover and oops! The exhaust elbow had came loose. I shut it down and started pumping water. No critical failures. The clamp on the elbow came loose and it took on enough water to sink a third of the oil pan. I checked over everything and went to start it again... (I have a push button start in the engine compartment for observational and solo operation purposes) the engine cranked freely (as if the plugs were out) and the timing belt was not turning at all. My better judgement and mechanical knowledge tells me that there is a shear key or pin on one of the shafts. This is my first volvo. Any help or any idea of what to expect would be great. I have the clymers manual but its about as useful as my anchor/engine at the moment.
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,855
Re: aq125a crank not turning

The starter turns the crankshaft, the crankshaft pully spins the timing belt. Is the crankshaft pully turning when you turn it over? If not theres your problem, if so, the belt is broken.
 

geoffreyc1212

Recruit
Joined
Sep 2, 2013
Messages
5
Re: aq125a crank not turning

It is spinning the crank. The timing belt is tight. That's what confused me. Its spinning freely as if the spark plugs are out but the cam isn't moving at all. Is it possible that the timing belt is slipping on the crank pulley?
 

captmello

Captain
Joined
Jun 30, 2008
Messages
3,855
Re: aq125a crank not turning

Its spinning easily because there is no compression, or, because the timing belt is damaged and not turning the camshaft, etc. The timing belt has teeth and cannot slip unless it is badly damaged.
 
Last edited:

geoffreyc1212

Recruit
Joined
Sep 2, 2013
Messages
5
Re: aq125a crank not turning

I did alittle checking today and the teeth on the timing belt are worn down to a sharp point not even touching the bottom of the grooves on the pulleys. I'm pretty sure that explains my problem, and my backfire issue. I couldn't imagine it being in time with the belt in that condition. Its been that way for sometime. My engine compartment is spotless. I'll focus on that this weekend. Any input on a walkthrough windshield seperating, and how to correct the issue? A new floor is in the works, and I'm throwing options around from a wood deck, to fiberglass. Either will cost about the same but I love the look of wood in a "modern" boat. Open to ideas as well.
 

geoffreyc1212

Recruit
Joined
Sep 2, 2013
Messages
5
Re: aq125a crank not turning

I installed the new timing belt, and wow! I can't believe I got this boat for $200!!!! I've had it out twice since and it runs perfect!
 

500dollar744ti

Senior Chief Petty Officer
Joined
Jul 23, 2012
Messages
691
Re: aq125a crank not turning

Edit:// ^^^ Just read your recent response, you can disregard the following info but I'll still post it in case someone stumbles on this thread in the future.

It is spinning the crank. The timing belt is tight. That's what confused me. Its spinning freely as if the spark plugs are out but the cam isn't moving at all. Is it possible that the timing belt is slipping on the crank pulley?

You are saying the timing belt is spinning the camshaft pulley but the camshaft is not turning? If so then the dowel pin that locates the cam in place has broken, usually from improperly torquing the bolt.

If the crank is spinning but the timing belt is not spinning, you could have a stripped crank gear, that's common enough, or it could have wiped some teeth off the belt itself.

Lucky for you the engine is non-interference so once you get the cam turning as it should, it'll fire right up.

Might be a good chance you stripped teeth off the timing belt. Those belts are not designed to last for 10 years even if it is just sitting.
 
Last edited:

geoffreyc1212

Recruit
Joined
Sep 2, 2013
Messages
5
Re: aq125a crank not turning

That's exactly what happened. I noticed the belt jumping alittle as it was cranking. I'm amazed they last at all with the pressure the pump applies on the system. I am going to attempt to machine a gearset, or sprocket and chain that would be able to withstand some abuse and not be so vulnerable. As for now its a completely different boat. Not a speed demon by any means but it is fun. The part is fairly simple to install and very cheap. Could be done in the water in 15 minutes. Part number for the aq125a is 95032 and is a dayco part number. Ill probably switch to gates next season, and for the price I wouldn't be opposed to replacing the part yearly. Old worn belts can be a lifesaver in a pinch. I feared I had broken a keyway to begin with. I have a bad habit of overthinking. I also mentioned my windshield seperating. Is there any way to bring the two halves back together? It does need a floor and stringers. That's a winter project. I have a whole new floorplan for it. I want it to last though.
 

500dollar744ti

Senior Chief Petty Officer
Joined
Jul 23, 2012
Messages
691
Re: aq125a crank not turning

No need to try and over-engineer something new, just change the belt every 5 years, it won't let you down.
 
Top