volvo penta aq125a coolant leaks out cap

[shagnatious]

Ok i have a 1982 bayliner trophy fisherman with a volvo AQ125A motor runs fine but when we got the boat running at 3800 rpm the temp rose and we lifted the hood and coolant was leaking from the cap. we dropped the rpms to about 3100 and it stopped leaking. The cap is rated at 13psi. Is that the correct cap? or can any1 give any insite

 

[Don S]

Re: volvo penta aq125a coolant leaks out cap

May be a bad cap, have it pressure checked or replace it. They don't last forever.

 

[familyguy]

Re: volvo penta aq125a coolant leaks out cap

when we got the boat running at 3800 rpm the temp rose

It went from what temp (?) to high (how high?) to cap stopped leaking. Did the temp go back down?

 

[shagnatious]

Re: volvo penta aq125a coolant leaks out cap

we were at about 3800 rpm when it started climbing it got up to about 250 degrees, then we totally shut down to idle for about 30 seconds temp started to drop we decided to idle back towards boat ramp and it ran fine unless we climbed over 3100 rpm we wouldn't let it climb back up so it stayed right at 180 the whole time we stayed under 3100 rmp. we replaced the coolant when we got it home, looking at the cap it looks new and had pressure when we took it off about 30 minutes after running it, i just bought this boat from a navy guy. the cap is clean and the spring has good tension. Also i was wondering if i just go and replace it it 13 psi correct??

 

[Don S]

Re: volvo penta aq125a coolant leaks out cap

When was the last time the raw water pump impeller was replaced? What shape is the exhaust manifold in? Is the heat exchanger clean?

 

[familyguy]

Re: volvo penta aq125a coolant leaks out cap

we were at about 3800 rpm when it started climbing it got up to about 250 degrees, then we totally shut down to idle for about 30 seconds temp started to drop we decided to idle back towards boat ramp and it ran fine unless we climbed over 3100 rpm

Is this something new or does it always do this when you run at 3800 rpm? If new, maybe your t-stat is sticking

we replaced the coolant when we got it home

Was it clean or did it look dirty, rusty?

Also i was wondering if i just go and replace it it 13 psi correct??

Sorry, don't know what the correct cap for your cooling system is.

 

[jerryjerry05]

Re: volvo penta aq125a coolant leaks out cap

Replace the cap.
The overheat could be 2 problems.My first guess is the exhaust manifold is clogged and not allowing enough water to pass. Remove the exhaust hose/bellows.Check the end of the manifold for corrosion and blockage.
Second would be the heat exchanger in the coolant housing.It gets clogged with sand/mud/weeds etc. You can try to remove it and back flush or dip it in muratic acid.Don't dip too long as it will eat it eventually.Or take it to a radiator shop.I've had some succes at the radiator shop.J

 

[captmello]

Re: volvo penta aq125a coolant leaks out cap

Let's not forget the ever popular intake fitting on top of the intermediate housing, just under the ujoint bellows.

It's easy to check. Pull the hose off and have a look.

This one came off of an aq125.

As you can see from the posts, there are many ways to overheat that engine.

 

[shagnatious]

Re: volvo penta aq125a coolant leaks out cap

i cannot answer the question as when the impeller was replaced for certian, as i have just bought this boat tuesday, maybe i should have asked specifically. I believe it has in this season he told me a list of items, ones i remember are carb rebuild, plugs, changed from points to electronic ignition, new gas tank, new wash down system. He told me so much i can't remember every thing he said. I should have brought a tape recorder. He is in the navy, had check lists every manual, had little quick references, study guides on everything in this boat, He might have shed a tear when i pulled it away. The coolant was very clean when it was comming out almost new it was neon green. This is my first i/o and just learning how they function.

 

[Don S]

Re: volvo penta aq125a coolant leaks out cap

The first thing to check on any overheat problem is the impeller. They can be damaged by any number of reasons. Even an unseen plastic bag over the intakes can damage them. You didn't run the engine without water to the drive did you???

 

[telstar1]

Re: volvo penta aq125a coolant leaks out cap

For me the most coomon ovrheat cause is something ie kelp over the intake. When I notice an overheat condition first thing I do is slow down, back up to clear off any weed etc,, and try again. If it got to 250 you were not paying anywhere near enough attention to gauges. Yikes thats hot. Id guess you blew renough coolant out that there wasnt enough left to allow proper cooling afterward anyway.At that temp the coolant is likely boiling and has to come out somewhere.Like the rad cap. Try it again with full reservoir and watchful eye on gauges. see what happens.Changing impellor a good idea IMO.Try not to let it get to 250!

 

[shagnatious]

Re: volvo penta aq125a coolant leaks out cap

No i didn't run motor in drive without water. lol almost funny question to ask but i bet there are people who do. I wasn't at helm when it started to over heat i went to back to check on the noise i heard. when i found out it was coolant leaking out cap i went back up and friend was driving and didn't even look at it til i said coolant was comming out cap. He is not as cautious as i and i will have to learn that some day. as for kelp or bag. we were in the channel in our bay which is sand not really anything but sand except in some places near shore that have some seagrass. checked it when it happened seen no bag and it was clear. I gonna run it again this weekend with a carefull eye and see if it repeats that episode. I just took it in when it did it last time, brought it home refilled with 50/50 antifreeze.

On another note the guy i got this from says max cruising speed is 3800rpm but my book says 4500rpm, any one know what is best for running it. I will run it at 3800 which i did that day, but it was only running 12-13knots. It would be nice to get a little more speed, but not at the cost of the engine.