Volvo Penta overheating and the solution!

[flyinverted]

You've seen a million posts and a million replies on overheating. I've never seen the fix posted online for my exact issue so I thought I'd share with you my experience.

2002 VP 5.0 GXi with VP DP-SM outdrive

Overheated on plane and had to limp back to the dock.
Fuel pumps shot due to overheating so I replaced them individually.
Not able to pick up water via muffs when she did previously for 5 years
Yes I changed the RSW impeller many times
Thermostat changed several times
Verified plenty of incoming water when not on plane
Mechanic found a cracked nipple in the outdrive and that nipple does come out of the water when on plane.

That did not fix the issue and I overheated again.
I first cruised 30 minutes out of my harbor then at 3,000+ RPM the temps rose until the alarm sounded.
Back at idle the temp would quickly drop.

Due to the overheat I pulled the heads and had them resurfaced and had valve job done.
Pulled the exhaust to find very clogged water passages. Replaced them as well.
I know somewhere during this troubleshooting I pulled and replaced the block mounted water circulation pump as well.
I stuck a water hose in the block and got the same amount of water coming out as was going in.

After all put back together I took her out for a run.
Guess what.. overheated again with the exact same specs.

Back on the trailer, I did a literal smoke test by using a Redline smoke machine and pumped smoke into the RSW intake hose that goes onto the RSW pump.
Absolutely no smoke visible in the engine compartment verifying no hose leaks around the engine.
Took a look at the outdrive and there was plenty of tell tale smoke near the water hose nipple. (water intake ports were taped shut)
My mechanic took the outdrive apart again to find the gimbal housing had corroded/deteriorated hole where the water tube nipple mounts.

Here is mine on the left and a new unit on the right. The o-ring on the nipple was no longer sufficient to seal that hole. I've yet to buy a new gimbal housing, so we just generously sealed up the nipple in the mounting hole with 5200. Smoke tested OK, now to let cure for 72 hours.

This is a trailer boat that is rinsed with SaltAway after every outing.

Mechanic said this is a carryover issue from the OMC/Cobra days and a known issue for him, but nobody ever mentions it online.

Hope this helps those with an annoying unsolvable overheat on plane.

http://www.stevesimages.com/chap/gimbal-hole.jpg


Smoke testing video:
https://www.youtube.com/watch?v=fKLp8dC1CAI&feature=youtu.be

 

[BRICH1260]

I had something similar happen, except that the plastic nipple that joins the aluminum housing to the rubber hose broke. The half of the nipple was left in the hose and the other half was left in the pivot housing.

VP needs to consider upgrading this plastic part to something more durable, perhaps a brass fitting.

 

[Lou C]

Great troubleshooting, the Volvo design has to suck water from the drive up and forward so it makes sense that it could suck some air in when the boat is on plane. The Cobra that uses the same transom design has the pump in the outdrive, so its pushing water from the drive up and forward so it might not be as prone to overheating due to this cause.

 

[Scott Danforth]

I had something similar happen, except that the plastic nipple that joins the aluminum housing to the rubber hose broke. The half of the nipple was left in the hose and the other half was left in the pivot housing.

VP needs to consider upgrading this plastic part to something more durable, perhaps a brass fitting.

prior to the plastic part was a cast aluminum part that died every 2 years due to corrosion. the plastic part has a life expectancy of a bit more than 5 years prior to the plastic getting brittle. Brass, aluminum and stainless dont play nice together in a salt environment, hence the reason the part is plastic. Brass would permanently be stuck in the drive as the drive corrodes around the brass if brass was used

its a maintenance item that gets attended to with the bi-annual drive maintenance when you replace bellows, inspect everything, grease u-joints, etc....you are removing your dive for the proper maintenance, correct.

 

[flyinverted]

prior to the plastic part was a cast aluminum part that died every 2 years due to corrosion. the plastic part has a life expectancy of a bit more than 5 years prior to the plastic getting brittle.

I guess getting 14+ years out of the nipple was good then! It's a 2002 I bought in 2012. I will be adding the nipple to the inspection/replacement routine. They're very inexpensive. Water test in 48 hours!

 

[Jammer864]

Thanks for taking the time to share the solution.

 

[BRICH1260]

Be sure to properly lune the nipple threads with a good underwater grease, it will make it much easier to get out the next time.

 

[flyinverted]

Following up for a confirmation that the sealing of the space around the nipple/o-ring with 5200 fixed the issue. For the first time in almost a year I was able to get on plane and keep her on plane with no overheating. If you look at any of the used VP gimbal housings out there, you'll see the hole of for the nipple is no longer round and true, but the rest of the housing looks like new. Yep that's why it's for sale.

 

[lmartz68]

I have been fighting this problem for about 2 weeks. I really appreciate the video, as it shows where the leak is coming from. I am checking mine this weekend when I get some time, but it makes complete sense that would be the issue. Thanks for posting, was driving myself nuts!

 

[Rockrunner99]

I am having the same problem where if works fine at idle but overheats at speed. Did all the normal stuff but she still overheats and funny thing only on the port side. The exhaust system on the right is much hotter to the touch so will pull it apart to see if there is any blockage. If not guess I’ll pull the lower unit.