AQ131D Exhaust Manifold

Hey guys, i have a question about an exhaust manifold problem on a Volvo Penta AQ131. First a little background. About 6 years ago my uncle was given a 1989 Barrette with a volvo penta AQ131D. When my uncle got the boat we cranked it up and took it out. It started fine but would only get up to about 3000 RPM. The guy that gave the boat away said he had a friend work on the carburator and he might have not adjusted it correctly or might have not rebuilt it right. So my uncle just parked the boat and it sat for about 4 more years as he did not want to spend any money on the boat. 2 years ago we tried to crank the engine and it was locked up. He then pulled the head off and found one of the pistons locked up. He soaked it with oil and was able to free the piston. He started trying to figure out why the piston was locked up and pulled one of the exhaust manifolds off. He found it was very rusty and a hole inside the manifold and assumed water got pushed up into the valve and in the cylinder causing the piston to freeze.

Now my uncle said he would give me the boat if i wanted to try and fix it. He currently has the exhaust manifold pulled off and the heads pulled off. Would a hole in the exhaust manifold cause the loss of power when running the boat years ago? Does it sound like a worthy project? If that would have caused the loss of power what else should i look for when trying to get motor running again. I have not looked at the engine in a while but he said the cylinder that was locked up had a little pitting. Thanks in advance for the comments!

As far as my experience with engines goes i am familiar with outboards as i have rebuilt my 1979 115 Johnson but have never worked on any I/O's.

Re: AQ131D Exhaust Manifold

Welcome back...

Those volvo motors have a reputation for being quite expensive to rebuild. Your lack of RPM originally could be any number of things. Unless the hull, deck and interior are in great shape, rebulding the engine will cost more than an operating, used boat.

The other option would be to try to find a comparable used car motor or used boat motor to swap into your boat. This could be a cheaper way to go, but again, the rest of the boat needs to be worth the time and money, and this is assuming you do all the labor yourself. I hate to see another Baretta head to the land fill, but some projects are just not worth it.

So whats the rest of the boat like? has it been sitting outside all this time?

Re: AQ131D Exhaust Manifold

The manifolds the place the water would come from.Sounds like it's bad.Go thru the carb.
The low rpm ? I doubt that would slow it down. Could be a fuel restriction/vent line clog?Bugs get in and build nest in the vent hose.Bad pump?
Volvos can be very expensive.The manifold 350$ ??? Good luck J

Re: AQ131D Exhaust Manifold

The boat has been outside with a cover on it. I haven't looked at the boat to close in a while but as i recall the interior and hull were in pretty good shape. I don't know about the deck, i might have a chance to go look at it and check it out a little closer this weekend. Is there any way i could check for other possible problems without the engine running? If indeed the exhaust manifold was not the cause of the low rpm could i put the bad manifold back on and see if i can get the boat running to try and find the other problem. I found an exhaust manifold for $209 at http://marineengineparts.com/shopsite_sc/store/html/page472.html I would hate to pass up an opportunity to get a nice boat running if i would just need a new exhaust manifold and unclog a vent line, but at the same time i don't want to start spending money and have to keep spending money to get this boat on the lake. Thanks!

Re: AQ131D Exhaust Manifold

thats a good price on that manifold.

what about the corroded cylinder? Post some pics of the dismantled motor. Running it with a bad manifold is not a good idea, IMO. However, being a fresh water cooled engine, you could remove the impeller and run the engine with just the old manifold in place but not hooked up to the exhaust rubber and exhaust pipe, and run it with no water hooked up for up to a couple minutes, for testing on the trailer only. For setting the timing etc. (someone correct me on this if I've forgot something)

The rest of the drivetrain will also need attention after sitting for so long.

You need to consider all the factors before you start spending.

You'll have a hard time testing it without being on the water, under load.


Go over the entire boat looking for rotten wood. Seats, deck, stick your hear down in the ski locker. If its carpeted, pull the carpet out, check the stringers on both sides of the locker. Check the rear bulkhead in front of the motor for rot, and delamination.

Post pic, we love pics.

Re: AQ131D Exhaust Manifold

Thanks for the help. I hope to go look at the boat this weekend. If i do i will take some pics and post them. What should i be looking for when checking the stringers?

Re: AQ131D Exhaust Manifold

redraider08 said:

Thanks for the help. I hope to go look at the boat this weekend. If i do i will take some pics and post them. What should i be looking for when checking the stringers?

Click to expand...

Your looking for soft spots, rot, delamination. tap the stringers with something hard. It should sound solid and have a tap, tap, sound, low, hollow, thud sound. Push at them with your fingers, feel for soft spots. tap on the transom as well, especially under the cutout for the outdrive.

I would expect to find some rot in most boat the age, just how much...you'll have to find out. Good Luck.

Re: AQ131D Exhaust Manifold

Attached are some pictures i took this weekend!

Re: AQ131D Exhaust Manifold

Here is a picture of the cylider with the locked up piston before i cleaned it up. As you can see from the picture there is some pitting. The exhaust manifold has a rather large hole rusted out in it. The hull looked to be in pretty good shape. There was a couple of soft spots in the floor and the pad on the back of the boat is bad, but the seats and carpet would look pretty good with a little TLC.

Re: AQ131D Exhaust Manifold

I cleaned of the block and the head. I would like to get the engine back together and just see if i can start it up before i spend any money on it. I I'm not to worried about the soft spots in the floor. My wife and i would like to buy a newer boat as we have a 79 ranger bass boat right now that we try to wakeboard off of. If i could get this boat running without spending much money it would be a big upgrade for the next couple of years untill we can afford a newer boat. Let me know what you guys think. Thanks!

Re: AQ131D Exhaust Manifold

One more pic.

Re: AQ131D Exhaust Manifold

Well, it's a gamble. But, it can't really hurt to try running the motor and seeing what happens. You still don't know the condition of the outdrive or intermediate bearings, etc, etc...

Have a look in the restoration forum and see what people say about free boats.

I must admit, I'm skeptical, but if you want to go ahead with it, I'm sure you can get the info you need from the guys on this site.

Its a good lookin' boat, sure looks like mine.

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Re: AQ131D Exhaust Manifold

That is a nice lookimg boat! Would it be ok to buy a used exhaust manifold? Is there any way to test a used manifold and what useally goes bad on it? I found a couple on ebay that are 1/3 the price of a new one. Thanks!

Re: AQ131D Exhaust Manifold

Used manifolds can be rusty, freeze damaged, clogged, or perfectly good. Personally I wouldn't buy one. A bad manifold can damage your engine is short order.

Re: AQ131D Exhaust Manifold

That sounds like a good idea! You replied right as i made a new thread for the question. http://smartolive.com/smartolive/volvo-four-cylinder-manifold-vo418.html This looks like a great deal! Has anyone ever used this website? I did some research on it and couldn't find anything on it. That gets me thinking maybe it's to good to be true!