Volvo Penta AQ131A & 275 OutDrive

Sebastian996

Recruit
Joined
Dec 5, 2022
Messages
3
Hello Guys
I just bought my first boat and I intend to do a general overhaul of the Volvo Penta AQ131A and Outdrive 275 engine.
The previous owner gave up the boat because the engine was overheating. He changed the exhaust manifold, water pump, thermostats and some other small parts.
First of all, any suggestions are welcome.
The big request would be if you could help me with a repair manual for the Outdrive 275 and a parts catalog for the AQ131A.
Thank you
 

kenny nunez

Commander
Joined
Jun 20, 2017
Messages
2,630
There are 2 areas on the drive that could be the problem. The hose fitting mounted on the suspension fork will rot off allowing air to get into the water stream. The other is the “O” ring that seals the lower gear case to the mid section allowing air in also.
Sierra # 18-2777 Or Volvo# 854031 water hose connection
18-2775. 875822 molded hose
18-0606. “O” ring kit to re seal the lower gear case water pipe.
 

sctbirdguy

Cadet
Joined
Jul 24, 2017
Messages
18
I have the same engine and have posted here as well. (You can find my threads by looking for overheating Volvo Penta 230b) I had/have 2 threads going and I haven’t found a fix. Biggest head scratcher I have encountered and I have fixed or replaced everything but the heat exchanger.

The outdrive parts mentioned above can be an issue however, all you have to do is replace a piece of the intake hose in the engine compartment with a clear hose. On my boat I have a copper line from the outdrive to the raw water pump and it has a 8”-ish rubber hose with an elbow in connecting the two pieces of copper. I temporarily replaced the rubber hose with a clear hose from HD. If the water in the hose has bubbles those outdrive parts are leaking. If not, you are good. I found a big helper to sit in the back and ran mine at idle and on plane and we did not see any bubbles.

The list of items to check and/or replace:
- Outdrive parts mentioned above plus the s-hose. This will all be proved with the hose test I mentioned above
- the raw water pump
- the onboard antifreeze water pump
- the belt that drives the pumps
- the heat exchanger (internal) clean by radiator shop
- the thermostat
- any leaks for raw water tubing from the outdrive through the raw water pump, through the heat exchanger and out the exhaust (buy the o-ring kit)
- the exhaust manifold
- the rubber exhaust coupler

Next is the engine. If it has been overheated the head should be resurfaced and a new head gasket installed. Look for clean oil. If it is milky you have a head or head gasket problem. If antifreeze is milky or being consumed you have a head or head gasket problem. You could have a cracked block or exhaust manifold but I really doubt it. If you dig into the engine look for cracks on top of the block between cylinders and water ports.

Make sure the timing and dwell are correct. Timing can cause overheating.

Let me know if this works and reach out with questions. I think I know as much about this engine as the original engineers at this point.
 

Sebastian996

Recruit
Joined
Dec 5, 2022
Messages
3
I have the same engine and have posted here as well. (You can find my threads by looking for overheating Volvo Penta 230b) I had/have 2 threads going and I haven’t found a fix. Biggest head scratcher I have encountered and I have fixed or replaced everything but the heat exchanger.

The outdrive parts mentioned above can be an issue however, all you have to do is replace a piece of the intake hose in the engine compartment with a clear hose. On my boat I have a copper line from the outdrive to the raw water pump and it has a 8”-ish rubber hose with an elbow in connecting the two pieces of copper. I temporarily replaced the rubber hose with a clear hose from HD. If the water in the hose has bubbles those outdrive parts are leaking. If not, you are good. I found a big helper to sit in the back and ran mine at idle and on plane and we did not see any bubbles.

The list of items to check and/or replace:
- Outdrive parts mentioned above plus the s-hose. This will all be proved with the hose test I mentioned above
- the raw water pump
- the onboard antifreeze water pump
- the belt that drives the pumps
- the heat exchanger (internal) clean by radiator shop
- the thermostat
- any leaks for raw water tubing from the outdrive through the raw water pump, through the heat exchanger and out the exhaust (buy the o-ring kit)
- the exhaust manifold
- the rubber exhaust coupler

Next is the engine. If it has been overheated the head should be resurfaced and a new head gasket installed. Look for clean oil. If it is milky you have a head or head gasket problem. If antifreeze is milky or being consumed you have a head or head gasket problem. You could have a cracked block or exhaust manifold but I really doubt it. If you dig into the engine look for cracks on top of the block between cylinders and water ports.

Make sure the timing and dwell are correct. Timing can cause overheating.

Let me know if this works and reach out with questions. I think I know as much about this engine as the original engineers at this point.
Thank you so much for all info's.
Currently I have removed the engine from boat. First I will check the compression and after I will try to start it and do some checks on stand.
I'm taking it slow. I hope i will take it back to life 😂
Thank you again.
I will write again with updates.
Wish u a Happy New Year !!!
 

QBhoy

Admiral
Joined
Mar 10, 2016
Messages
7,176
Definitely compression test her. They are quite well known for warping the head on them after the mildest of overheat. Check the cap on the expansion tank is correct and holding its pressure as it should (until it shouldn’t obviously). Not a fan of these engines to be honest. Loads of them had issues locally to me back in the day. Often they were repaired countless times after and even replaced with the another from a scrap car of suitable donor ship. Ultimately most ended up with a GM 3litre in then instead.
 

sctbirdguy

Cadet
Joined
Jul 24, 2017
Messages
18
Thank you so much for all info's.
Currently I have removed the engine from boat. First I will check the compression and after I will try to start it and do some checks on stand.
I'm taking it slow. I hope i will take it back to life 😂
Thank you again.
I will write again with updates.
Wish u a Happy New Year !!!
I look forward to hearing about your progress.

What is your plan with the boat? If you plan to get it running and want to use it and you have it out of the boat already I wouldn’t bother compression testing it. You will have to rig up a way to start it, get water to it etc and it’s not worth your time. You don’t know the history other than it overheats and someone gave up on it. As mentioned below the heads warp easily and for 30 mins of work removing the head and a $30 head gasket just take the head off, bring it in have it cleaned up and gone through. It will be $200-ish dollars. I did this and cleaned up the valves on my own while I was at it. I also put new valve stem seals in, camshaft seals, the valve hushers, etc. it’s cheap, easy and you now know the head and all the valves are good. Plus you can visually inspect the head and block for cracks or defects.

I compression tested mine and it showed good. No more than 5 psi differential and I think between 164 and 170 psi…I think those were the numbers. It then lead me down several paths that were expensive rabbit holes and I was in the exact situation you are in. Overheating previous owner gave up etc.. It was a waste of time. If you bought the boat and was told it ran great but you wanted to test it out of curiosity that makes sense.

On top of that mine will run all day in the driveway and never get hot. You have to take it to the lake and work it before it starts to over heat. I bet yours is the same unless you have severe damage.

Again keep me posted interested in your solution.
 

sctbirdguy

Cadet
Joined
Jul 24, 2017
Messages
18
Definitely compression test her. They are quite well known for warping the head on them after the mildest of overheat. Check the cap on the expansion tank is correct and holding its pressure as it should (until it shouldn’t obviously). Not a fan of these engines to be honest. Loads of them had issues locally to me back in the day. Often they were repaired countless times after and even replaced with the another from a scrap car of suitable donor ship. Ultimately most ended up with a GM 3litre in then instead.
What kind of issues did these engines have? I don’t know anything about their history other than the Volvo guys love them and boost the crap out of them and the ones in these boats are severely under powered.
 

Scott Danforth

Grumpy old guy who plays with boats
Joined
Jul 23, 2011
Messages
42,470
What kind of issues did these engines have? I don’t know anything about their history other than the Volvo guys love them and boost the crap out of them and the ones in these boats are severely under powered.
cant compare a turbo application in a car with a naturally aspirated engine with wet exhaust in a boat. you have to understand valve overlap and reversion along with gearing and load
On top of that mine will run all day in the driveway and never get hot. You have to take it to the lake and work it before it starts to over heat. I bet yours is the same unless you have severe damage.
on the hose in the driveway you are forcing water up the drive.

in the water the water must be pulled by the waterpump and pushed by the forward movement of the boat.

most likely your water neck casting on the drive swivel is bad and your raw water pump is sucking air while in the water
 

sctbirdguy

Cadet
Joined
Jul 24, 2017
Messages
18
cant compare a turbo application in a car with a naturally aspirated engine with wet exhaust in a boat. you have to understand valve overlap and reversion along with gearing and load

on the hose in the driveway you are forcing water up the drive.

in the water the water must be pulled by the waterpump and pushed by the forward movement of the boat.

most likely your water neck casting on the drive swivel is bad and your raw water pump is sucking air while in the water
I was just wondering what problems these engines have.

My issue with my boat is not with the water neck and my guess is the original poster doesn’t have this problem either.

I am pretty confident he has a warpped head and or bad head gasket along with a clogged heat exchanger core.
 

Scott Danforth

Grumpy old guy who plays with boats
Joined
Jul 23, 2011
Messages
42,470
Hello Guys
I just bought my first boat and I intend to do a general overhaul of the Volvo Penta AQ131A and Outdrive 275 engine.
The previous owner gave up the boat because the engine was overheating. He changed the exhaust manifold, water pump, thermostats and some other small parts.
First of all, any suggestions are welcome.
The big request would be if you could help me with a repair manual for the Outdrive 275 and a parts catalog for the AQ131A.
Thank you
link to on-line parts manual for the US. https://www.volvopentastore.com/

euro link. https://www.marinepartsexpress.com/

link for manuals https://www.volvopenta.com/en-us/service-and-support/your-engine/manuals-and-handbooks/
 

Scott Danforth

Grumpy old guy who plays with boats
Joined
Jul 23, 2011
Messages
42,470
I was just wondering what problems these engines have.

My issue with my boat is not with the water neck and my guess is the original poster doesn’t have this problem either.

I am pretty confident he has a warpped head and or bad head gasket along with a clogged heat exchanger core.
all volvo penta AQ series drives have a bad raw water inlet casting on top of the pivot tube unless they changed to the latest plastic one. the prior white-metal ones last 3 years in fresh water and less than 2 years in salt water.

you replace them every time you pull the trans every year to inspect the u-joints and bellows

the easy test is a clear hose from the raw water pump to the HX. if you see bubbles, you are sucking air.
 
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