running hot under load

[baylinercapri]

I have a 1987 bayliner capri with an volvo AQ131 in it. It runs around 175 when around 3000 RPM. If I start going 3500 RPM it starts to ping some and the temp rises to between 200-225. Both the closed and fresh water seem to be working okay. Any help would be appreciated.

Thanks
John

 

[subcrx]

Re: running hot under load

sounds like poor circulation

 

[bomar76]

Re: running hot under load

The first 25 things to check in this situation (overheat) are all:
Check / replace impeller
They realisictally last 2-3 years.

After that, check for clogged (with rust) risers, retarded ignition timing, chunks of old impeller in system, bad thermostat, bad hoses sucking air, etc.

 

[JAL51974]

Re: running hot under load

I'd bet poor circulation too. When on plane you might be sucking air at a spot that is normally under water when at idle? What drive?

 

[Maclin]

Re: running hot under load

There is a fitting on the outdrive intermediate housing that a molded hose connects to and goes to the transom, there is another hose inside that then feeds the raw water pump. Those fittings corrode quickly for some reason and can let air in on plane. The fitting is underwater at idle and slow speeds.

There is a test for this, Don S has posted it in a related thread. Basically it involves taping off the inlet grate slots on the outdrive and plugging the drainage hole on the font of the bullet (just above the skeg), then unhooking the raw water pump inlet hose and putting a garden hose in and seal it with a clamp then run water backwards to the outdrive. If that connector or hose is leaking then water will come out there before it blows the tape off.

To fix it, if that is the problem, you will need to remove the upper housing which will give you a chance to check out the drive bellows and drive shaft ujoints. One the upper housing is off it is a fairly simple latter to get the hose off and change the fitting. Changing the hose out is alittl more difficult as it pokes thru the transom from the inside, but is worth doing once you have all that apart. Also might as well put a new drive bellows on when you put it back together.

 

[baylinercapri]

Re: running hot under load

The impeller seems to work okay it sucks water in at idle or hooked to a hose. I tested the thermostat also and that opens and closes fine. How do you know if you have a clog somewhere and how do you flush the system out?

Thanks,
John

 

[baylinercapri]

Re: running hot under load

The drive is a volvo penta 275.

Thanks
John

 

[baylinercapri]

Re: running hot under load

Thanks I am going to try that.

John

 

[jerryjerry05]

Re: running hot under load

Might be two problems.Manifold clogged.Or that motor has a heat exchanger in the front of the motor in the big red (box) thing on the front of the motor. It will need to be taken out and back flushed.If your lucky you might be able to clean it out.Possibly clean with muriatic acid,just don't leave it in too long or the brass will disolve.Good luck.the exchanger is costly$$$$ Check manifold first. Jerry

 

[Maclin]

Re: running hot under load

Here is the post that Don S made with the link to the pdf file download page for testing cooling components....(it has flushing procedures also for finding obstructions)



http://forums.iboats.com/showpost.php?p=1696368&postcount=7




I had this problem, was fine in the water until I planed out for a while, and it would bring some water in from the muffs but not enough for me to feel good about, so I began looking for the problem, again mine turned out to be that fitting.

 

[bomar76]

Re: running hot under load

The impeller seems to work okay it sucks water in at idle or hooked to a hose.

Thanks,
John

Well SEEMS to work ok is not "verified that it is working as designed", so I'd go back and check that it does before I went any further.