3.0 volvo penta gs with cobra sx cooling problem

Mark Meili

Recruit
Joined
May 31, 2016
Messages
5
This 1996, 17' Crestliner Sportfish was my Dad's and has been having sporadic overheating problems for as long as I can recall. As far as I know, it has never been in saltwater. I inherited it last year and it ran good for the first few outings, but then overheated. No pressure to the hose running into the thermostat housing. I replaced the impeller which had missing splines. I believe I chased down all the pieces which went as far back as the power steering cooler. It ran good for a couple times then back to overheating. I replaced the thermostat to no avail. I noticed a weld was broke and leaking on the power steering cooler so I fixed it but to no avail. I can blow air unrestricted from the PS cooler back through the thermostat and raw water pump. The firt time i tried blowing air from The PS cooler through the intake port it seemed like there may have been some blockage. I ran water back and forth from the PS cooler to the intake and it seemed to free up. I can get water to feed up through the intake to the PS cooler only if I hold the muffs down really tight. I can get the motor to stay cool if I prime the raw water pump by first holding the muffs tight. It will not prime otherwise. Perhaps a crimped intake hose in the lower unit or something along those lines? Re-check impeller? Risers? I am a novice auto mechanic at best and I am at a complete loss and feeling more than a little beat up after losing the first few rounds to this I/O. Any help is greatly appreciated.
 
Last edited:

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Put a clear hose between the pump and the thermostat housing to see if you are getting air bubbles.

What year is this boat and what is the model number of your drive/engine.
 

Mark Meili

Recruit
Joined
May 31, 2016
Messages
5
Supreme Mariner. Thanks for your reply. It is a1996 3.0GS Volvo Penta motor with a Cobra SX drive. I can get the serial number and such tonight, if need be.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Your PS cooler should be on the suction side of your water pump and its in between the pump and the drive. Actually kinda surprised you had impeller pieces in the cooler. They should go in the direction of the water flow which is away from it.

When was the last time the drive was removed? When it was removed, was the oblong o-ring between the drive and the pivot housing replaced? That is a point where it could suck air especially when you are in the water.
 

Mark Meili

Recruit
Joined
May 31, 2016
Messages
5
Thank Bruce. I only know that the lower unit was replaced around 10-15 years ago by a small shop that probably hadn't seen a lot of volvo pentas, after my Dad hit a rock. This oblong oring issue sounds like it is worth looking into. I can see how once the motor is shut off, bits of the impeller could back flow to the exiting side of the power steering cooler with gravity at play since the impeller and pump housing sit higher than the power steering cooler. There were no bits on the intake side of the power steering cooler. I even had little bits jamming up the thermostat spring.
 

Mark Meili

Recruit
Joined
May 31, 2016
Messages
5
My Dad also had the same shop address the tilt trim last year as it wasn't keeping the motor up for long. Whatever he had done with that (could not find receipt) did not work as the motor will completely drop on its own in a half hour.
 

Mark Meili

Recruit
Joined
May 31, 2016
Messages
5
Would this same outdrive seal also be a candidate for the cause of slow water intrusion inside the boat?

The boat will obtain a couple inches of water overnight in the motor compartment.

Are we talking a new billows(sp?) kit?
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
No, that would either be caused by a bad u-joint bellows or a rotten transom. You should be puling your drive annually and changing the bellows every 5 years.
 
Top