Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

[shawnn82]

I have a 22' 1986 bayliner trophy with a volvo penta 275 outdrive. I took it out last week and we had around 2-3 foot seas. The fastest i could get it to go was 7mph on gps. With the drive all the way in the down position (with the what i think is the reverse latch in the locked position)> I could get it up to 2800 rpm and it would go 7mph and then push it past 3000 and it sounded like it was struggling. I couldnt get it to go past 3000 rpm no matter what.
This is my first boat and im not sure what is goin on. Any ideas?
P.S. Out of the water the engine revs up past 4000 rpm without any hesitation.
Maybe i have a wrong prop on there? ANy idea what prop i should be having?

 

[captmello]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

Yes, you could have the wrong prop on the boat. Did the boat come with that prop? What is the pitch? You should be reaching close to 5000 RPM at WOT once you get the boat on plane. Revving the motor in neutral, or on the trailer is not a good test and could damage the engine if done repeatedly, so don't do that anymore.

Before swapping props, I would make sure the engine is in good tune and is in good condition. I would start with a compression test. You should have between 140 and 170 psi. If the compression tests ok, I would do a full tune up, unless its been done recently. If you have points and a condenser, swap those out as well and use a dwell meter to set the points gap.

Once these are checked out, and the boat still doesn't want to plane out, a different prop may be in order.

That is a big boat for that motor so you want it in top running condition to get it to perform for you.

Good luck, let us know what you do and how it goes! Make sure to ask questions if your unsure about anything.

 

[Don S]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

You have a lot more than the prop. Figuring between 150-200 rpm per inch of pitch change, you would have to decrease your prop 10" to 13" to get your WOT rpm where they need to be. That is not going to happen.
Here are a list of things you need to check out to find what your problem is. http://forums.iboats.com/showthread.php?t=295070

 

[shawnn82]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

Thanks for the quick reply guys, heres what i found
Starting with the prop, i may be wrong but it seems to be of spec
Material: Aluminum
Diameter: 15?
Pitch: 17?
Blades: 3
Rotation: Counter (Counter-Clockwise)
Part number : 814612

The engine had a tune up before i took her out. Compression on all 4 cylinders was good between 160 and 165 on all 4. Dont remember the exact numbers.
Carb was rebuilt as well. Did an crancase oil / filter change. Fuel was swapped out for good fuel. New fuel filter. Did not do a fuel systems test. Will have to do that. The boat mechanic went over pretty much everythign. Throttle + shift cables and linkages were checked. No signs of engine overheating when i took it out last. Keep in mind we were out for a good 8hrs. Didnt let 7mph top seed ruin our fun though. From reading around this boat / engine setup should be able to do 25 - 26mph at 4000 - 4800rpm.
As far as improperly loading, there were 6 of us on the boat well below the weight capacity rating on the boat. All goods were loaded on the bow insude the cuddy(approx weight of goods 50 - 80lb). We had 2 people on the starboard side and 3 on port. 1 in the cabin.
My trim tabs at the time were in the retracted position and movin them up or down had no impact on speed( or not any that i could tell anyway). This drive doesnt really have a trim feature.
also, no marine growth on hull or drive. This is a trailered boat.

Any suggestions?

 

[Don S]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

This drive doesnt really have a trim feature.

No, but it does have a cross pin to prevent the drive from going too far down. If that pin is missing or to low it will make push down in the water and plow through the water, not plane up on top of the water.

 

[shawnn82]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

No, but it does have a cross pin to prevent the drive from going too far down. If that pin is missing or to low it will make push down in the water and plow through the water, not plane up on top of the water.

Well the cross pin can mount on 3 holes all of which are like 1/2 inch apart. Originally it was on the hole closer to the transom. I moved it yesterday to the furthest most hole away from the transom. Will moving it an inch away make the difference between 7mph and 25? I havent taken it out yet.

 

[captmello]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

Well the cross pin can mount on 3 holes all of which are like 1/2 inch apart. Originally it was on the hole closer to the transom. I moved it yesterday to the furthest most hole away from the transom. Will moving it an inch away make the difference between 7mph and 25? I havent taken it out yet.

Having the pin in the furthest out hole, causes my bow to rise significantly and makes getting on plane tough, even with my V8. I think you have found your problem.

The big difference in your speed will be getting on plane. Once on plane, you can check your speed and WOT RPM, etc.

Your trim tabs should help get you on plane as well. Start off with them in the down position. Once on plane you can adjust theme to a setting that feels right.

Let us know what happens.

 

[shawnn82]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

Having the pin in the furthest out hole, causes my bow to rise significantly and makes getting on plane tough, even with my V8. I think you have found your problem.

The big difference in your speed will be getting on plane. Once on plane, you can check your speed and WOT RPM, etc.

Your trim tabs should help get you on plane as well. Start off with them in the down position. Once on plane you can adjust theme to a setting that feels right.

Let us know what happens.

HEy guys, finally took it out after a busy couple of months. I set the pin to the furthest out hole and the bow does rise up but still no getting past 7mph. I had a mechanic go over everything to do with the engine and he found no fault. Doubt I have a spun hub. The way he tested it tho was by throwing it in gear and trying to move the prop by hand. Ofcourse it wouldnt turn so we concluded it wasnt a spun hub. I called bayliner and they said the prop should be a 15"(diameter) x 17"(pitch). Thats what i have on there now. part number 814612. This is a Left Hand turn Prop. Hypothetically if i use a RH prop on a LH drive (or vice versa) , would i see a similar result (not going past 7mph)?

 

[sqbtr]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

With that size boat the pin will probably have to be run in the most forward hole. The tune needs to be perfect, and the advance checked. Ask your mechanic what he set the dwell to and what base time is, then ask what your total advance is?

 

[awdurland]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

I have the exact same boat, When I bought it I had the same problem it would dog around 9mph and never get to plane. I started by looking to see if my tabs were functioning, which they were not. I corrected that and when I start out I keep my tabs up go to full throttle and move the tabs down it then pulls itself up on plane and when I reach a speed arpund 18 mph I bring the tabs up this tops me off around 24. I started doing this with the points system and have since upgraded to electronic ignition.

 

[shawnn82]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

I have the exact same boat, When I bought it I had the same problem it would dog around 9mph and never get to plane. I started by looking to see if my tabs were functioning, which they were not. I corrected that and when I start out I keep my tabs up go to full throttle and move the tabs down it then pulls itself up on plane and when I reach a speed arpund 18 mph I bring the tabs up this tops me off around 24. I started doing this with the points system and have since upgraded to electronic ignition.

i have checked the tabs, infact i replaced the hoses for both of em and have done what you tried and still no luck. Do you happen to have the part number or any sort of information for the electronic ignition? Im thinkin thats the next step.
What throws m e off though is in gear, on the trailer. it will rev up to 5000. Of course i didnt leave it at that high rpm's but realy quick jus to test it out, in gear it will go as high as 5000 rps which is within range for this boat. UNder load though in the water. It maxes out at 3000Rpm. ANy ideas?

 

[awdurland]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

Somebody will probably pipe in with the electronic ignition number, if not I will grab the box next time I'm in the boat. If your tabs are working I think it is a dwell or timing problem. I set my timing at idle and at 4000 rpm if I remember right that was part of the problem as well. I know dwell was a pain with this cap having to take it on and off and I had a stripped screw that was letting it slip I believe.

 

[Don S]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

What throws m e off though is in gear, on the trailer. it will rev up to 5000.

That is a useless, non-test. You could take 2 of the spark plugs out of the engine and it would go over 10,000 rpm without a load.

Have you checked the gear ratio on your drive? If you have a V8 ratio (1.61) in the dive, I don't care what prop you put on it, it's not going to get on plane.

 

[awdurland]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

My electronic ignition is a pertronix 2842, but I fixed the problem before I upgraded. The dwell and timing were key, have you made sure they are set correct. If you need them I can look it up, I took them from a thread on this site years ago. Pretty sure I printed it and put it in my boat binder.

 

[shawnn82]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

That is a useless, non-test. You could take 2 of the spark plugs out of the engine and it would go over 10,000 rpm without a load.

Have you checked the gear ratio on your drive? If you have a V8 ratio (1.61) in the dive, I don't care what prop you put on it, it's not going to get on plane.

How do i check the ratio?

 

[shawnn82]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

My electronic ignition is a pertronix 2842, but I fixed the problem before I upgraded. The dwell and timing were key, have you made sure they are set correct. If you need them I can look it up, I took them from a thread on this site years ago. Pretty sure I printed it and put it in my boat binder.

Im actually havin a mechanic come over and check/adjyst the dwell and timing. Id appreciate it if you could look up that info for me. Thanks

 

[awdurland]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

The rebuild book I have calls for 62 degree of dwell angle +/- 3 degrees. The timing should be 6 deg BTDC 0- 850 rpm and 32-36 deg BTDC @4200 RPM. I cannot find the old thread from here I think one of the moderators commented that they run better at a different setting I don't remember what it was I believe my motor liked these settings the most.

 

[shawnn82]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

That is a useless, non-test. You could take 2 of the spark plugs out of the engine and it would go over 10,000 rpm without a load.

Have you checked the gear ratio on your drive? If you have a V8 ratio (1.61) in the dive, I don't care what prop you put on it, it's not going to get on plane.

I found a lower unit with a ratio of 2.15:1. Would this work for my setup? However, the seloc manual i have suggests a 1.61:1 ratio for the 275 drive specifically. i Did find oxidised points in the distributor. Ordering rotor, contact point, and cap. Will do timing and dwell once i get those parts.

 

[captmello]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

the 275 can be any ratio. you want the 2.15 for the aq131.

 

[shawnn82]

Re: Volvo Penta AQ131A w/275 Stern Drive wont get up to plane

the 275 can be any ratio. you want the 2.15 for the aq131.

Will just getting the lower unit alone work with my existing upper unit. Or do i get both of em? Not sure how it works.