I have been fighting an overheat issue with this engine for two years. It's closed cooling, I/O dp-s drive. I've worked on it myself and with a Volvo certified mechanic. The risers are two years old and rechecked. The raw water pump replaced. The thermostat checked. The outdrive pulled, gaskets and one hose replaced. Last year it would overheat even at low rpm's. After the work performed now it does not overheat at the mooring, even running it at 2000 rpm. What's happening now is running a couple of miles at 3000rpm, it overheats severely and will not cool down even running at limp speed. When it cools all the way down and not moving at speed it runs fine. I'm at a loss here and really could use some help. Could it be a computer issue, maybe retarding the spark?
Overheat hell 2006 Volvo 5.7 gi-f
- Thread starter pvalen
- Start date
How would the coolant pump be checked? (Not raw water pump, right?) Also, maybe the serpentine belt? Everything seems to be turning, put belt dressing on it. Do they stretch over time? Tensioner seems OK. Could it be internal engine, like a head gasket or computer not timing right? Will put backflushing the exchanger coolant side but can't figure out how something could get in there, being closed and all.
Simplify your search. At cruise speed , are they staying cool enough so you can comfortably keep your palm on the top of each riser/elbow indefinitely ?
If yes, look to the FW side, ...if no, you have a RW side flow issue .
If yes, look to the FW side, ...if no, you have a RW side flow issue .
Something I didn't mention. Launched the boat couple of days ago. Went from the yard to my mooring, about four miles, various speeds, mostly lower rpm's. One stretch I had it about 2500 rpms. All OK until the mooring. I left it idling while I hooked the boat up. When I got back to the wheel, the temp gauge was over 200. When I started it later, it ran OK. That's when I took it out for a fast run and had to get towed back.
Does your motor have one of those flush connections at the motor to hook up a garden hose? My 2003 does and one time I did not have the cap on and experienced overheat at low RPMS. It took about a while before noticing my error. That was after a t-stat change and several other tests. If the cap is not tight or hose has a hole you will not have a sealed system.
- Joined
- Sep 28, 2002
- RO Number
- 10314
- Messages
- 851
Are you sure it is really overheating and not a gauge issue?
Check the temp of the intake manifold right under the the thermo housing, this should be within 10* of the dash gauge if checked with an IR temp gun. If its normal (160-175) and the temp gauge on the dash is at 200+ then you have sending unit, gauge or wiring issue.
If its really overheating...
1)is this a salt water boat kept on a mooring?
2)have you verified that you have adequate raw water flow from the impeller to the heat exchanger?
3)if not I bet you might have barnacles growing in the water intake area of the lower unit. I had a mild running hot condition, (ie increased from 160-165-->175-185) over the course of 2 seasons. Checked impeller, manifolds, risers, etc. Checked raw water flow from impeller with boat in the water and it was low. I knew I had some barnacles growing in that water intake area. Split the drive, removed the water screen in the lower unit of the Cobra, cleaned out the water intake area. Back to 160-165 temps and risers normal temp even after coming off plane (110*-100* or so). Previously I had 175-185 engine temps and 140-160 riser temps.
Always verify adequate raw water flow with the boat in the water as per manufacturer's specs as a first step. Then make sure risers/manifolds are clear.
Check the temp of the intake manifold right under the the thermo housing, this should be within 10* of the dash gauge if checked with an IR temp gun. If its normal (160-175) and the temp gauge on the dash is at 200+ then you have sending unit, gauge or wiring issue.
If its really overheating...
1)is this a salt water boat kept on a mooring?
2)have you verified that you have adequate raw water flow from the impeller to the heat exchanger?
3)if not I bet you might have barnacles growing in the water intake area of the lower unit. I had a mild running hot condition, (ie increased from 160-165-->175-185) over the course of 2 seasons. Checked impeller, manifolds, risers, etc. Checked raw water flow from impeller with boat in the water and it was low. I knew I had some barnacles growing in that water intake area. Split the drive, removed the water screen in the lower unit of the Cobra, cleaned out the water intake area. Back to 160-165 temps and risers normal temp even after coming off plane (110*-100* or so). Previously I had 175-185 engine temps and 140-160 riser temps.
Always verify adequate raw water flow with the boat in the water as per manufacturer's specs as a first step. Then make sure risers/manifolds are clear.
The heat exchanger has been checked, no blockage. I am at a mooring with phenominal growth going on last couple of seasons. Definite overheat checked with temp gun. Pulled the outdrive last fall, changed out a hose and the water gasket. I have suspected something growing inside but the mechanic I had said it's just a tube in there? If low flow I guess I'll have to haul the boat and get into that. Never split the drive, don't know much about it. Thanks for all the input. Its appreciated.
- Joined
- Sep 28, 2002
- RO Number
- 10314
- Messages
- 851
Yes there is just a copper tube with 2 grommets connecting the upper and lower drive units, but in the area just above the water intake holes in the lower unit, inside you will get barnacles growing depending on the fouling conditions where you are. Since I removed the water screen I can rod out that area (Cobra has 4 large holes, Volvo and Merc use 6 smaller ones I think, but no water screen) and I plan on splitting the drive every 3 seasons. My mechanic who has worked on I/Os moored/slipped in salt water for years has said that this is something you need to do. It will eventually causing overheating, and if you never take it apart, it will be difficult. I figured out a way, to get the upper and lower apart, without breaking anything. Ask if you want to know...takes a while to type...
Post back if you find a solution to your problem....
Post back if you find a solution to your problem....
Well, I quit gabbing and went to work. Two days with a Volvo certified mechanic last year failed to find the problem, so I figured if you need a hand, look to the end of your arm. To start, I hooked up a legnth of hose on the outlet of the raw water pump , with a clear section, to check volume. It pushed water over the end of the hose 1" when held at the height of the flame arrestor. However, I noticed lots of air in the water. So then I hooked up a section of clear hose in the intake of the pump. Still had the air. I then hooked up a 12v air pump to the intake line, figuring the head of water in the drive would give me a few pounds pressure. The was no pressure at all. Looked at the drive and found all the air coming out the very top of the drive. That seems to indicate failure of the hose or thru hull fitting in that area. I then clamped off the hose between the oil cooler and transom to pressurize the line itself, finding a small leak in the oil cooler. So, looks like a haul out for me and looking for a good mechanic (hard to find). It seems the mechanic I had was using water mainly in the water and muffs in the yard which did not make the leak location obvious. He also said the cooler was not an issue. He also had me replace the pump, which was a waste of money.
- Joined
- Sep 28, 2002
- RO Number
- 10314
- Messages
- 851
OK you have a Volvo SX series, right? What I did was remove the drive and set it on this stand, I also had built a wood one some years back. The Volvo SX is very similar to my OMC Cobra except for the cone clutch shifting in the upper gear unit. What I did was put a piece of all thread through the hole for the trim ram rod and put two bolts, one in each lower mounting hole in the front end of the drive. Then I put a scissor jack under the two bolts, and one under each end of the all thread. Jack each one carefully and slowly. It will pop right off. Saves you prying, cursing, etc. Will not break anything.
You might have a crack in the water hose fitting that is in the pivot housing. Take a look at a Volvo parts diagram, it is on the left side of the pivot housing. They basically copied the OMC transom design, the fitting, the bellows are all similar.
here is a pic from my drop box.....
https://www.dropbox.com/s/nbiqnmzm0zmltaw/Cobra 5.jpg
Now if yours is the newer design, this method should still work, but you will have to carefully check how the water travels from the upper gear housing to the transom mount. That may be where your problem is.....(air getting pulled in)....
You might have a crack in the water hose fitting that is in the pivot housing. Take a look at a Volvo parts diagram, it is on the left side of the pivot housing. They basically copied the OMC transom design, the fitting, the bellows are all similar.
here is a pic from my drop box.....
https://www.dropbox.com/s/nbiqnmzm0zmltaw/Cobra 5.jpg
Now if yours is the newer design, this method should still work, but you will have to carefully check how the water travels from the upper gear housing to the transom mount. That may be where your problem is.....(air getting pulled in)....
Very clever, Lou! I like the way you find solutions to keep things working! Please tell me more about that metal stand... Looks like an automotive engine stand with a modification in the form of a fork to slip the outdrive into then support it from the cav plate. Plus some clips to stabilize it on the fork. Sounds like a mod I could make for my stand, except mine doesn't crank up and down...
Before we moved I had a friend who could fab anything. Today's prices, I'll have to improvise. Somebody, Charlie, I think, has one welded out of small angle steel maybe 3/4 or 1" on a side, that works off a little hydraulic floor jack. Trolley Jack I guess some call them. The adjustable height is important if we want to slip the outdrive back into the transom assembly... And have a paved surface... And...