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AQ131A Overheating on plane

M

mpnutter

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"Hello all!

I believe this

"Hello all!

I believe this question has been beat to death but I really need to ask it anyways because I am at my wits end and I think I have done all that I have found here.

I have a 1987 Baretta with an AQ131A.

The boat will run fine in the driveway with muffs on it all day long, as it will cruising.

As soon as I hit plane, the temp rises and overheats.

I have done the following...

Replaced impeller
Replaced thermostat
Replaced intake hose and connector on outboard.
Replaced cracked exhaust hose
Replaced radiator cap

I am not finding any leaks on the inside.

I have the service manual for the model.

Please any ideas would be greatly appreciated of what to look for.

I don't want to have to replace the manifold until I have tried to figure out if it is really needed.

Thanks in advance!

Mike"
 
"How old is your exhaust manif

"How old is your exhaust manifold? If it is over five years and you run in salt water, I would suspect it is scaled, reducing water flow and leading to the engine overheating.

Pull the manifold and see what it looks like.

What rpm band are you planing at?"
 
"1) Remove the copper pipe

"1) Remove the copper pipe going to the bottom aft of the exhaust manifold and stick a screwdriver or a small rod into the manifold. If it comes out muddy, that's a sign of possible obstruction;

2) Remove the wide hose connecting the exhaust manifold to the exhaust pipe and look at the water passages between the outer an inner part of the manifold: if choked with rust/scale, throw the exhaust manifold away and get a new one.

3) Stick a garden hose at the bottom of the manifold (into the hole where the copper pipe is connected) and flush the manifold with water. See how easily (or difficult) the water flows out of the water passages. That will give you an idea of the manifold's internal condition.

4) Block the water intake grids in the outdrive with duct tape, then remove the suction copper pipe from the raw water pump, stick a garden hose into the copper pipe, pressurize it and look for leaks between the garden hose and the grids: any water leak will pinpoint a source of air ingress.

Hopefully one of the above should do it for you."
 
"All,

Sorry for a the delay

"All,

Sorry for a the delay in this response. I lost track of this post.

Since the post, I have done the following.

1.) I have stuck a hose in the exhaust pipe and I seem to have good flow.

2.) I have removed the copper insert in the heat exchanger and spray this. Note: This seemed to improve the time it took to overheat.

3.) Someone told me to pull the thermostat to allow more water to enter. Note: I think this overheated worse.

4.) I removed the copper insert in the heat exchanger again and acid dipped it in a hydrocloric acid mixture designed for copper heat exchangers. Note: This removed a lot of scale and I will be testing this later today."
 
"mike i just went through this

"mike i just went through this and trust me when i tell you if that sucks in the least bit of air will over heat try sqeezing the muffs together to force more water in,depending on how many feet your hose is will make a difference,also with out a ? DO NOT RUN THAT WITH OUT A THERMOSTAT,also make sure u have good water flow coming from the back of the boat when your running......"
 
"Drew, I think you were referr

"Drew, I think you were referring to running this on muffs. I can run on muffs all day long without an overheat. It is only on load in the lake.

I tested the engine after acid dipping the copper insert and saw a lot more time before overheating. After overheating, I put the engine in neutral and ran the engine and it cools down almost instantly.

I had put a clear hose on the intake and see absolutely no air coming into the hose.

I replaced the copper insert today to see if this would help even more if there is a blockage in the unit and will be testing tomorrow night.

Thanks,

Mike"
 
"You folks have given me some

"You folks have given me some new imformation that may just help me,
I have a 230 2.3 B volvo engine, the freash water pump is leaking from the front seal.
so I ordered a new pump , should be here next week
anyway , when it's running on the muffs the temp never climbs over 145
I put it in the lake last night and ran it as my mechanic said I could do,
The temp gauge went way up to the 200 mark.
Will this new fresh water help to stop this and make it cool so I can run it....I only run this boat 2 maybe 3 times during the summer on the lake, I may run it more this summer due to fuel prices in my cruiser.
great boat for the weekedays , cruiser on the weekends."
 
"so then running a high temp w

"so then running a high temp would be somewhat normal.
I also remeber I had covered the hole in the bottom of the foot with duct tape when I was running it on the muffs in the driveway.
They might of had something to do with thenhigher temps also...
one mechanic told me also, it may be sucking air when on plane , so once I get the new raw water pump it should make a considerable difference.
Do you agree????"
 
"If it sucks air on the plane,

"If it sucks air on the plane, then the raw water hose connector in the outdrive is likely corroded/perforated. Do a search in the forum for <font color=""0000ff"">raw water hose connector</font>, this has been discussed countless times."
 
"I did not get the boat in the

"I did not get the boat in the day I thought, but I did yesterday. I had already replaced the raw water hose connector a long time ago.

After replacing the copper insert in the heat exchanger, I can now go about 6 miles at 3700 RPM's until it slightly overheats. This about 7 times more than I got after acid dipping the old coil.

Then if I put the boat in neutral and rev it at about 2500 RPM's for about 30 seconds, the boat cools and I can do it all over again.

Obviously that coil was about 90% of the problem, but there is still a little something happening.

Mike"
 
I have only had it to about 45

I have only had it to about 4500 RPM's. Gauge goes to 6000 RPM's. It will go farther but I never pushed it.

Mike
 
"I see you still have not chec

"I see you still have not checked the exhaust manifold. You may want to remove it and examine the riser. If partly plugged with rust and scale, don't waste your time trying to clean it: get a new exhaust and that will likely solve you rproblem. BTW, the one in the link has a price difficult to beat:

http://cgi.ebay.com/ebaymotors/Volvo-Penta-Marine-4cyl-Exhaust-Manifold-1978-199 0_W0QQcmdZViewItemQQcategoryZ31285QQihZ019QQitemZ290243056423QQrdZ1QQsspagenameZ WDVW


Also, make sure you check the raw water strainer and it is clean. Further, make sure the alternator belt is not slipping, as that would slow down the water circulation pump."
 
"El Pescador,

Thanks for th

"El Pescador,

Thanks for the link, I actually went ahead and ordered one either way.

What is the maximum RPM's that is safe to run this engine at?

Thanks,

Mike"
 
"Mike, download the owner'

"Mike, download the owner's manual from this link, and look at the specifications. The answer to your question is there.
happy.gif


http://www.volvo.com/volvopenta/global/en-gb/marine_leisure_engines/engines/out_ of_production_engines/out_of_production_engines.htm"
 
"Hi!I've got exacly the sa

"Hi!I've got exacly the same problem as Mike Nutter and I will look into the points suggested by El Pescador. However, it would be great if someone could give me a link to a webpage showing some graphics of how things are put together.

Also, I changed the exhaust manifold three years ago. Is it at all possible that it can be faulty after such a short period?"
 
"Stefan, more than looking at

"Stefan, more than looking at points, you may want to throw them in the garbage and replace them with an electronic ignition kit (Hot Spark or Pertronix 2842). Also, if you are goint to do your own tikering, you may want to get hold of a copy of the Seloc or Clymer repair manuals, they are a great source of information.

Three years seem to be a very short period for an exhaust manifold to deteriorate, even if ran in salt water. However, a manifold can be clogged due to a number of reasons (sand, mud, faulty raw water pump, etc)."
 
"What does the ignition have t

"What does the ignition have to do with the cooling of the engine?

I've looked at the seawaterpump, replaced the thermostat and tested the plate heatexchanger.

In my mind there may be two faulty things left; the exhaust manifold or the cooling liquid pump. I will try changing the exhaust manifold (although it shouldn't fail after only three years). Anyone had a problem with a failing cooling liquid pump?"
 
"Stefan, please receive my mos

"Stefan, please receive my most sincere apologies for my screw-up. It seems that this morning, trying to answer in a rush about 10-12 postings before leaving work, I misread in yours the word "points".
blush.gif


What type of drive do you have?"
 
"I have exacly the same setup

"I have exacly the same setup as Mike, i.e. AQ131A+VP275 from 1987 on a boat model called Caprice 195CC. and as I said before I've tested all things I thought was obvious without any improvement and as far as I can figure out I've got the gas manifold and the cooling liquid pump left to deal with (and I think they both are unlikely causes to the problem...). Do you have any other suggestions?"
 
"The most common causes for ov

"The most common causes for overheating I can think of are

barnacles or other marine growth inside the outdrive cooling passages

the water intake grids in the outdrive are clogged.

a perforated/corroded raw water hose connector in the outdrive,
http://www.marineengine.com/parts/part_details.php?pnum=SIE18-2778&returntopage= sierra_marine/sierra00826.htm


a faulty or incorrectly assembled raw water pump; i.e. the impeller is broken, the Woodruff key is not installed or the water pump coupler ( http://www.marineengine.com/parts/part_details.php?pnum=SIE18-3106&returntopage= sierra_marine/sierra00816.htm )
is not in place

the raw water strainer is clogged

the heat exchanger is choked with scale

the exhaust manifold is choked (internally corroded, with scale & mud)

the alternator belt is loose

There could be other causes, like a piece of impeller vane or a foreign object stuck in the cooling pipes or somewhere in the cooling system."
 
"Hi, I've now dismatelled

"Hi, I've now dismatelled the entire cooling system (except for the cooling liquid pump which seems to be very difficult to remove) and all pipes and other stuff inkl the exhaust manifold seems to be clean, i.e. no signs of anything stopping the seawaterflow. Since the exhaust fumes are coming out of the back of the drive there shouldn't be anything blocking the water either (the boat is in the water so I can't control what's coming out of the pipe). The belts seems to be tighty aswell. Any suggestions on where to go next? Could there be an engine problem?"
 
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