running out of hope...penta aq125 misery.

[2stroke1971]

LONG story short: Bought an old Bayliner, an 84 with the volvo AQ125 motor. Supposedly ran.
Would only backfire for me at first.

*Replaced timing belt because the old one was crappy, and it was off by two teeth.

*Rebuilt Seawater pump--had a blown seal and bad bushing and cross piece.

Still, just a backfire, so I checked compression.

I had 150 pounds on 1,2 and 3 but zero compression on 4.
Pulled head. Broken valve on number 4..(burnt and crumbled)

*Rebuilt the head, all new exhaust valves...one was broken, the other 3 were cracked (burnt)

Cranking and cranking...nothing. its not even trying.

Good spark on all new plugs.
wiring order correct.

double checked engine timing, correct.

Put timing light on it, under cranking I have it set to about 6 btdc, although it drifts just a bit as its cranking.

I dont think fuel is making it to the cylinders. plugs seemed dry. And cranking it with plugs out, I would have expected it to be blowing some vapor, right?

There was a lot of gas pooled up in the intake when I took the carb off...flooded I guess, but Wouldnt it get sucked into the cylinders?

I put my palm against the intake hole as best I could with the studs sticking out, and it seemed to suck in pretty well.

Ive had the carb apart, it was clean, no obvious problems.

Ive worn the battery down three times. Not so much as a cough.


It has electronic ignition.

Im running out of energy.

Any ideas on what to do next? Why would it not vaporize fuel, or pull it in? The puddle in the intake is from the accel pump I imagine, as I was pumping it here and there through the 20 minutes of cranking.

 

[Don S]

Re: running out of hope...penta aq125 misery.

Go do a compression test again and come back with the results.

 

[pilotman]

Re: running out of hope...penta aq125 misery.

LONG story short: Bought an old Bayliner, an 84 with the volvo AQ125 motor. Supposedly ran.
Would only backfire for me at first.

*Replaced timing belt because the old one was crappy, and it was off by two teeth.

*Rebuilt Seawater pump--had a blown seal and bad bushing and cross piece.

Still, just a backfire, so I checked compression.

I had 150 pounds on 1,2 and 3 but zero compression on 4.
Pulled head. Broken valve on number 4..(burnt and crumbled)

*Rebuilt the head, all new exhaust valves...one was broken, the other 3 were cracked (burnt)

Cranking and cranking...nothing. its not even trying.

Good spark on all new plugs.
wiring order correct.

double checked engine timing, correct.

Put timing light on it, under cranking I have it set to about 6 btdc, although it drifts just a bit as its cranking.

I dont think fuel is making it to the cylinders. plugs seemed dry. And cranking it with plugs out, I would have expected it to be blowing some vapor, right?

There was a lot of gas pooled up in the intake when I took the carb off...flooded I guess, but Wouldnt it get sucked into the cylinders?

I put my palm against the intake hole as best I could with the studs sticking out, and it seemed to suck in pretty well.

Ive had the carb apart, it was clean, no obvious problems.

Ive worn the battery down three times. Not so much as a cough.


It has electronic ignition.

Im running out of energy.

Any ideas on what to do next? Why would it not vaporize fuel, or pull it in? The puddle in the intake is from the accel pump I imagine, as I was pumping it here and there through the 20 minutes of cranking.

Hmmm. I wonder.
I have to rebuild the Ford Mercruiser 160CI straight six in my just aquired 1968 T-bird tri hull. Kinda spendy. I was wondering if a rebuilt 4 cylinder 2.3 liter Ford marine engine might be an option. Not sure if it would pack enough punch to power this though. You might want to look at a rebuilt long block
for your boat as well. Fewer headaches, but more bucks.

 

[Don S]

Re: running out of hope...penta aq125 misery.

I have to rebuild the Ford Mercruiser 160CI straight six in my just aquired 1968 T-bird tri hull.

You don't have a Ford 6, that's a Chevy, look at your post. And no, a 2.3 isn't even close to an option.

 

[robjen1019]

Re: running out of hope...penta aq125 misery.

I know that when I set up a new install, I usually set the timing, and then have someone else turn it over. While it turning over I manually twist the cap till it starts.
You could dump a little gas down the carb and then turn it over to see if is starts.
Make sure it is firing on the compression stroke. Hook up a timing lite and remove sparkplug 1. Put finger in hole, and have someone turn it over. should feel a puff of air when the light comes on.
Could be a float adjustment problem, if fuel related.
If its backfiring It sounds like a timing problem.

Just brainstorming here.

 

[2stroke1971]

Re: running out of hope...penta aq125 misery.

HAHAHAHAHAHAHAHAH!!!



Well.... I had made a lengthy post about my progress up until this afternoon when I posted this one, so the complete history is here:

http://forums.iboats.com/showthread.php?t=377459

But anyway, I put a call in to my Brother, who is a professional mechanic, although automotive...he does have 40 years of experience. Right away, he said weak ignition system. Says he: Even a hurting 4 cylinder with burnt valves and low compression on one cylinder should TRY to do something.
This motor now has a valve job and should be good. I told him I even tried some ether, and it didnt even pop.

He told me a story of an old Saab, (hails from the same part of the globe as my Volvo) and they required a VERY small plug gap.

Stories abound back in the day that when the owners of these Saabs would put new plugs in, they would never start again. I started laughing.( I hadnt told him that I used new plugs) I put new plugs in after putting it back together. Before, when it at least backfired due to a broken valve, it was on the old plugs, and I DID think the gaps were crazy.

In fact, my better half was so concerned about my mental status, she was searching online, and found a post elsewhere about some poor SOB who replaced plugs in some sort of mercruiser, and all of a sudden it wouldnt start.Blah blah blah plug wires, firing order, etc...

Bottom line: I gapped the darned things (Autolite #63s) to .65mm , and first turn of the key it fired. Its stumbling, and sounds rough as hell, like maybe not all cylinders are firing but I didnt try too long because its late and I didnt want to disturb the neighbors. The plug wires are a bit suspect, a couple of the ends are loose. I wonder just HOW critical the gap is here. I just read the spec again, and it said .70mm. Wonder if that would smooth it out. Gawd.

the previous owner did say that he thought the carb needed a rebuild, Hell I dont know. Im just glad I got some signs of life anyway.
Tomorrow, I will give a better go and see what I can get out of it!

Thanks again everyone!

 

[Don S]

Re: running out of hope...penta aq125 misery.

Did you gap them a .65mm (Metric) or .065in (Standard US measurement in inches). Big difference.