Volvo Penta 5.7 gxi overheating

Nitetymme

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My Volvo penta 5.7 engine started overheating, at speed and idle. I replaced the entire raw water pump assembly. When I attach a water hose directly to the engine flushing bib, I get water out of the exhaust and everything seems to work properly. Engine runs fine. However when I put the boat in the water, at idle it immediately over temps and runs hot, 210 degrees. I have not been able to find any posts that suspect a water circulation pump may be at fault. Any suggestions?
 

Scott Danforth

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first, welcome aboard

most likely its not the water circulating pump

did you find the missing bits of your old impeller?
did you back flush the PS cooler and the incoming lines to the water pickup in the drive?
did you check the hose between the drive and the transom shield, especialler where it connects at the drive?
do you boat in salt water, and could your exhaust manifolds be plugged with rust?
 

Nitetymme

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Wow, that’s a lot to look for. Thank you for the reply. First of all there were no missing parts to my impeller. I am not sure what the PS cooler is. Maybe this is too much of a job for DIY. I am not familiar with the transom shield. I do not boat in salt water.If my exhaust manifold was plugged, what I still see water exhaust when I connect the water hose up to the flash bib on the engine?
 

Bondo

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Wow, that’s a lot to look for. Thank you for the reply. First of all there were no missing parts to my impeller. I am not sure what the PS cooler is. Maybe this is too much of a job for DIY. I am not familiar with the transom shield. I do not boat in salt water.If my exhaust manifold was plugged, what I still see water exhaust when I connect the water hose up to the flash bib on the engine?
Ayuh,..... Welcome Aboard,...... That test oughta rule out the exhaust,....
Now ya gotta check the water line from the drive's water pickup, through to the raw water pump's inlet fitting,.....
Unhook the raw water pump inlet hose, 'n back-flush it to the drive,....
 

Nitetymme

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OK, here is what I have done. When I connect the water hose to the flash bib on the engine which is connected between the outdrive pick up and the raw water pump. With the engine not running, water does appear to pour out of the pick up on the out drive. I disconnected the hose that comes from the water pump to the thermostat housing. When I start the engine, I get a good flow of water going to the thermostat housing. When I reconnect that hose I do notice a large amount of water leaking from the bottom bellows that sits between the outdrive and the transom. Could my problem be there? I would like to attach a couple of pictures so you can see exactly what I’m talking about.
 

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Scott Danforth

Grumpy Vintage Moderator still playing with boats
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pull the drive, look at the hose between the transom shield and the drive. specifically look at the fitting screwed into the drive. they are known to fail.
 

Lou C

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What year and what specific drive do you have? Is it an SX or SX-A?
I would try to find a document titled “Volvo Penta Overheat Diagnosis”, it is a PDF that is right from V/P and gives all the trouble shooting steps needed to narrow down the problem. Have you checked the thermostat (removed it from the housing tested in a pot of hot water using a radiator thermometer), the standard stat opens at 160 and should be fully open at 175-180. The stat functions as a gate valve maintaining a set temp of 160-175 or so. If it does not open the engine will surely overheat.
The exhaust system functions as the exit for the hot water leaving the engine, if the cooling passages in the exhaust system clog with rust it will over heat. These open non pressurized systems depend on a large volume of cooling water in and out to keep the engine & exhaust at the proper temperatures.
 

BRICH1260

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Make sure your blue cap flush port is tight and seating properly and has the O ring in it. If not, your pump will pull in air and you will lose the ability of the pump to pull in drive water. You might pull the impeller out and inspect it for damage due to the overheating.
 

Nitetymme

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pull the drive, look at the hose between the transom shield and the drive. specifically look at the fitting screwed into the drive. they are known to fail.
Is pulling the drive a DIY procedure? I have tools but before taking on this task I just need to know if it’s something that can be done myself? Where can I find specific instructions on pulling this particular drive, it is a DPS do a prop drive. Also, what runs through that bellows, any hoses or anything? Can that bellows be removed/replaced without pulling the outdrive?
 

Lou C

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Yes it is DYI but the drive is heavy and if you're older it can be tough on your back to get it back on. I use a drive jack to make it easy. The upper bellows has the driveshaft and u joints inside, the lower nothing, its just to quiet the exhaust, to change the bellows the drive has to be off, in fact the right way is to remove the part of the transom mount that the drive bolts onto with the 6 nuts (3 on each side).
I'd advise getting a VP shop manual before diving into this, yes there are a lot of posts here on it, and also on you tube, but I always advise getting the accurate information from the OEM before pulling things apart.
this boat is moored in salt water close to 20 years now that's why it looks like this but with regular maintenance it works just fine. A properly functioning cooling system should run from 160-175 on the gauge, with a 160 stat, and 140-150 with a 140 stat. Here's mine....with the 140 stat for salt water....
 

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bruceb58

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Is pulling the drive a DIY procedure? I have tools but before taking on this task I just need to know if it’s something that can be done myself? Where can I find specific instructions on pulling this particular drive, it is a DPS do a prop drive. Also, what runs through that bellows, any hoses or anything? Can that bellows be removed/replaced without pulling the outdrive?
I have been doing it for years although I have a drive stand so you will need two people to do it yourself. Remove the 6 nuts holding the drive remove where the rams attach to the drive, disconnect the shift cable linkage, disconnect the hold down bolt for the shift cable and it pulls right off.

To make it lighter and prevent damage, remove the props which you need to do anyway to drain the gear oil.

You need a socket on the end of a universal joint to get the 6 nuts off. I use a torque wrench and torque to the recommended sequence and torque as specified in the owners manual.

Make sure you replace to oblong water passage seal whenever you remove the drive.
 

Nitetymme

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Yes it is DYI but the drive is heavy and if you're older it can be tough on your back to get it back on. I use a drive jack to make it easy. The upper bellows has the driveshaft and u joints inside, the lower nothing, its just to quiet the exhaust, to change the bellows the drive has to be off, in fact the right way is to remove the part of the transom mount that the drive bolts onto with the 6 nuts (3 on each side).
I'd advise getting a VP shop manual before diving into this, yes there are a lot of posts here on it, and also on you tube, but I always advise getting the accurate information from the OEM before pulling things apart.
this boat is moored in salt water close to 20 years now that's why it looks like this but with regular maintenance it works just fine. A properly functioning cooling system should run from 160-175 on the gauge, with a 160 stat, and 140-150 with a 140 stat. Here's mine....with the 140 stat for salt water....
 

Nitetymme

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I really appreciate the time that you have taken, you have given me some good information. Before I tackle this job, I do have a few more questions. The bellows that we are speaking of, I presume that’s normal to have water in it, does it hurt or is it a sign of a problem if water is leaking from it as mine is? Given the information that I have provided so far, the engine appears to cool just fine with the water hose hooked up, so that tells me that the impeller is not pulling seawater from the out drive pickup. So I am assuming my problem is somewhere between the impeller and the out drive pickup? You mentioned a connection that usually goes bad, is there a high probability that that is where my issue is since everything else appears to be flowing properly? And yes I am old so I will build a support for the outdrive once it is removed. Lol Once this is done, is there a kit with any special gaskets or O-rings that need to be replaced when I put it back together?
 

Lou C

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Before putting it back on, you should check aligment with an alignment tool, and using the jack helps get it at exactly the right height. Engine alignment is a whole topic unto itself, once set right it usually doesn't change unless you have a boat with rot in the transom or engine mount pads, or bad rear rubber engine mount bushings. I have not had to change mine in all these years that I've been doing the drive maintenance (about 15 years worth).
Another trick I have used is to put a long thin screwdriver in the U joint cross, so I can turn the driveshaft just slightly so that the driveshaft splines will line up with the coupler splines. I find this makes it very easy to get it all the way on, usually it takes only a 1/8" turn or less to get those splines to align, kind of like doing a clutch on a manual transmission car.
It can hang up for a few reasons, one is the gimble bearing not being aligned, (this can be done simply with alignment tool) the other the other is not holding the driveshaft straight as you try to feed it in, and the last is the splines not lining up, that screwdriver trick works like a charm.
I use Evinrude triple guard grease on the driveshaft splines, motor oil on the 2 orings, not grease there. That odd shaped gasket, I stick it in place with the same triple guard grease it can shift out of place and cause the drive to suck in air.
 

Lou C

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I really appreciate the time that you have taken, you have given me some good information. Before I tackle this job, I do have a few more questions. The bellows that we are speaking of, I presume that’s normal to have water in it, does it hurt or is it a sign of a problem if water is leaking from it as mine is? Given the information that I have provided so far, the engine appears to cool just fine with the water hose hooked up, so that tells me that the impeller is not pulling seawater from the out drive pickup. So I am assuming my problem is somewhere between the impeller and the out drive pickup? You mentioned a connection that usually goes bad, is there a high probability that that is where my issue is since everything else appears to be flowing properly? And yes I am old so I will build a support for the outdrive once it is removed. Lol Once this is done, is there a kit with any special gaskets or O-rings that need to be replaced when I put it back together?
OK you have 2 bellows, the upper is the driveshaft bellows, there should never be water in that one, if there is it is cracked or torn and must be replaced, and you likely will have to replace the gimble bearing and maybe the u joints due to corrosion
The lower one, is the exhaust bellows, that is normal to have water inside, these don't really have to be replaced periodically but the upper one, as soon as you see small cracks in the folds, its time to replace it pre-emptively before it fails and costs you $$$. I've had them last 10 years but 5 is a safer interval. If you can store the boat with the drive level, the bellows tend to last longer than if the drive is left up.
There should be a V/P transom kit with the 2 o rings for the driveshaft and that odd shaped gasket that goes between the drive and transom mount. I use OMC gasket sealer on the 6 studs to keep the nuts from seizing up.

Other reasons why your impeller may not be picking up water:
1) there is a plastic water nipple in the transom mount (pivot housing is what I think they call it) if this cracks, due to improper winterization, it can suck air there
2) inside the drive there are 2 water tube grommets, if these are rotted, or burned from an overheat the impeller won't get enough water. There is a pipe that connects these 2 grommets, there was a member on here, who had the same problem, it turns out that there was a hole rotted in that pipe! But if he never split the drive he would have never found it. Once found, simple solution. For the water tube grommets the drive must be split (upper and lower gear housings) and it is really a job for a mechanic. I've done it on my Cobra just getting the bolts out and getting the upper gear housing off can be difficult. I have a trick for that problem though....salt water teaches you many tricks.
 

bruceb58

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If your boat is overheating just sitting in the water, nothing that is broken on your drive would cause you an issue since everything is under water.

When you are on plane, the water is forced up the drive so still unlikley that a crack in anything would be a problem either.
 

Nitetymme

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The over heating came when I dropped the boat in the water after replacing the impeller. I motored at idle speed and watched the temperature rise to 210.
 

Nitetymme

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Lou, in response to your item about other reasons my impeller is not picking up water...the plastic water nipple in the transom mount, is that on the outside of the transom? If on the inside behind the engine, I'm sol.

Also when you say there are 2 water tube grommets inside the drive. Are these accessible only when the drive is removed?

For both of these issues, are the accessed only when the drive is removed?

One thing I failed to mention. My speedometer has not worked in some time. I did notice that there is a plastic fitting that has broken from the drive that has a small hose attached that I'm assuming is the water pickup for the speedometer. It is broken off. Is it much of a concern?

Also, I don't know if you noticed, one of the photos I attached shows water coming out between the front prop and the housing when I use the engine flush connection. Is it normal for water to come from this location?
 

Nitetymme

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In the event I tackle this job, can you suggest where I can get the Alignment tool for my DPS drive.
 

bruceb58

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Personally, what I would do is, put the boat in the water, start the engine and pull the hose going to the thermostat and see if you are getting any water out of it.

There is no way I would be dissembling your stern drive.

You can buy alignment bars on ebay. Its the same alignmnet bar used for OMC Cobras, Mercruiser and Volvo drives.
 
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