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Overheat hell. 2006 Volvo 5.7 i/o dp-s drive

T

true blue

New member
I have been fighting an overheat problem for two years, myself and with a Volvo certified mechanic. Last year it would overheat even at low rpm's. Risers two years old and re-checked. Raw water pump replaced. T-stat checked. Determined problem was in the outdrive, since air coming in to the pump. Pulled the outdrive changed a hose and two gaskets, seemed to run fine after on the muffs. Just launched, drove to the mooring, (3 miles), all OK until idling while tying up, then looked at the temp, gauge was pinned. Went back later to investigate after it cooled and it seemed to run fine. Took it out about a mile, still OK, then speeded up. Started to overheat then and would not cool even when reduced to low speed. Had to get towed in. Before going out Suspected a slipping belt since the volts seemed to be going up and down so used belt dressing and checked the tensioner, seemed to be OK. Could it be internal engine or computer? Please help if you can.
 
Mind you, the following is just what I do and why....

Every Volvo I/O drive boat that I've owned (3 since 1964), I've converted to thru hull water pickup with strainers.

Why... Overheating due to: inlet holes on drive clogged with debris, little critters growing in drive passages, leaky water elbow, leaky gasket on water elbow, muck from close encounters with the bottom clogging up the system.

The thru hulls have not been 100% trouble free either. Some strainers are very picky as to how you tighten the cover nuts, all are picky about the cover gaskets. I now have an external strainer scoop. It too was problematic, but related to the mechanic who sourced it and installed it. For a 5.7 engine with FWC, a scoop with 0.077 dia holes is too small. While this scoop is the one for a 1-1/4 inlet, a conversation with the GROCO customer service guy (GREAT folks!!) recommended the next larger scoop, i.e., the one for a 2" inlet... which also has larger holes in the scoop screen. The GROCO inlet scoop I have is the one with a door on the scoop so you can clean/inspect the thru hull for little critters.

Also why... I have a T fitting and a garden hose bib valve on that T... winterization is a snap as well as flushing the system periodically with fresh water after using the boat. ( Turn off thru hule valve, connect short hose to bob valve ( since this is a brass part, it gets replaced every 3 seasons), put hose in 5 gal pail with water hose running into it.... NEVER HOOK UP A PRESSURIZED HOSE DIRECTLY TO THE INLET OF THE RAW WATER PUMP WITH THIS SETUP!

Since your drive is a 2006, that is not too young to have pinhole air leaks in the elbow on the drive, i.e., where the raw water hose connects to the drive. Even if the elbow is OK, it appears as if you had those gaskets replaced? Not cleaning the old gasket pieces off 100% can lead to air leaks with new gaskets. Some mechanics are lazy and do not totally clean off old gasket material.

On another subject: been chasing a very minor slow loss of antifreeze ( a pint a season). Discovered that when my mechanic installed the FWC kit on my brand new 5.7MIE some years ago, he apparently only installed the stainless blocking plate between the manifold and elbow... no gasket(s). Since new elbows are due to be installed (by me) this summer, will fix correctly.
 
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In order to completely trouble-shoot an over-heat scenario, follow the seawater path from the point of entry to the spent seawater point.
This means everything! Leave no rock unturned!

Look at the area where the seawater enters the lower unit.
Look for crustaceans that may have grown inside. Yes, I keep a plastic bag of these to show customers that this can occur.

Follow this path and examine hoses for interior delamination that cannot be easily seen from the exterior.

Make sure that all fittings are clear and free flowing.

Look at the suction hose. A small pin hole or suction leak will breach suction!
Pull a vacuum on the suction hose with your shop-vac.
Use shave cream at any suspect areas.
If the shave cream disappears quickly, you may have found a breach in the suction hose.

Look at the seawater pump impeller housing.
Use a dial indicator caliper to measure the impeller housing depth, and compare this to the impeller width.
The impeller should sit "proud" by .010" or so. If not... it will not work correctly.

Look at the impeller housing thrust surfaces. Any scoring may hinder the impeller's ability to pull water in.
Look at the impeller housing's cam. The cam must be in excellent condition in order to fold and un-fold the vanes correctly, and without causing a wear pattern in the vanes.


If raw water cooled, look at the T-stat housing ports. All must be clean and near pristine, and free from heavy rust scale.

With any Marine engine cooling, most all seawater is by-passing actual engine cooling demands.
This means that a lessor percantage of seawater is doing the engine cooling, while a greater pertentage of the seawater is going to and out the exhaust system.
Any restrictions at the exhaust system, will/may cause issues.

Look at the point of entry at the exhaust manifolds.
Perhaps pull the fittings and check them.

Next... look at the spent seawater transfer ports between the manifold and exhaust elbow.
These must be free of rust scale at either... and the gaskets must be a match to the transfer ports.

Somewhere within the elbows, there will be a mixing chamber. Make certain that the rubber couplers are not restricting this area.

Back-flow prevention flappers. If equipped, you'll also want to look at these.


Lastly.... you say that you've been fighting this for two years.
Question:
What has changed, if anything, as of two years ago?
IOW.... was any work performed prior to this problem?
Was the drive removed and re-installed?
Were any new parts installed?
Was a new impeller installed two years ago?
Did you suck up silt or sand into the cooling system?


The OEM system worked well at one time. Something has changed.
Your job is find out what this was/is.





.
 
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Thanks for the nice reply Ricardo. I do get a lot of marine growth, barnacles, mussels etc. due to the river I'm moored in. I'm trying to think of a way to make sure the tube in the outdrive is clear without pulling everything apart after hauling the boat. The raw water pump was replaced, didn't make any difference. Risers are new and rechecked. 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. So the overheat also happened in neutral at idle. I did give it a reverse to pick upthe mooring maybe that jostled some debris or something. My next move as I see it is check for air and/or adequate suction flow.
 
true blue said:
1.... I'm trying to think of a way to make sure the tube in the outdrive is clear without pulling everything apart after hauling the boat.

2..... My next move as I see it is check for air and/or adequate suction flow.
Click to expand...
Bear with me.... #1 is sort of an A$$ Kicking... but all in fun! :D

1.... That's the problem. This is not an area whereby you want to save yorself work.

You have two choices:

  • Do the work now and avoid engine damage.
  • Replace the engine later, and also do the work to find out what caused the problem in the first place, as to avoid a repeat.


2..... Yes!



Some factory worker put this all together, and it worked for years... but now it does not work.

The ole P of E (process of elimination) is your friend when used systematically and methodically.
Do one item only at a time, and do not move to the next item until the previous has been either found to be the culprit..... or has been eliminated.
You may not find it easily or quickly..... but you will find it.

.
 
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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.
 
Do you know of the radio talk show Car Guys from NY? Click and Clack?
One of their fixes is the lift the radior cap off, and to drive a new car underneath it.
It works 100% of the time. ;)
In a similar fashion, your mechanic is throwing parts at the problem, instead of looking for and finding the actual problem.
If we throw enough parts at any problem .... $$$$$$ .... we'll eventually solve it. :rolleyes:

**************
I would not circumvent any portion of the seawater system for trouble-shooting.
The problem needs to be found, and corrected.


Yes... one small pin hole leak will breach suction..... it's Physics!


Check for suction leaks with suction.... although if severe, you will find it.
Check for pressure leaks with pressure..... although again, if severe, you will find it.
 
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Right about the parts replacement guy, but finding suction leaks with suction would not have found my main problem, which was the thru transom fitting or assoc. parts.
 
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