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Results 1 to 14 of 14
  1. #1

    Angry Vovlo Penta 3.0 GS overheating and I don't know why

    Hey everyone. My name is Chris and I own a 1999 18 foot bowlder with a Volvo Penta 3.0 GS. Last summer the boat ran fine until the end, when I started to notice overheating. This summer the water hose going into the engine ruptured so now I need some help. I've checked the veins on the water pump and their fine. I've ran water through the exhaust manifold and back through the inlet and there was no obstruction of flow. I'm guessing somewhere in the internals there are bits of gunk that are causing all my problems, but I'm no expert. Any advice on back-flushing the engine or should I pursue a different coarse of action. Also the boat needs a thermostat and a new hose (obviously). Thanks for anyones advice.

  2. #2
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    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    Chris, sorry to hear about your overheating issue, but it happens to most at one time or another. Just search overheating and you find plenty of threads to guide you for what to look for.

    You didn't mention if it overheats at all times or just when idling or just when plained out. Also, is your boat raw water cooled or is it a closed system?

    Either way, some of the things that you can try are actually unbolting your risers and manifolds to see if rust is restricting water flow. Just because water flows through them doesn't mean it enough.

    Also, check to see if your thermostat is working.

    You can also drain you block and see if there is any gunk that got sucked up in there. Since your impeller was intact, it is doubtful there are pieces stuck in the water passages of your engine.

    Also, check the water connection hose on the drive to see if its cracked.

    Good luck.
    1994
    5.7 GI-PMDA
    AQ DP-C

  3. #3

    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    The engine sits around 120-130 F when idle or when slowly moving through the water. Once I push it up to around 2600 RPM however, Temp goes up. For a short while it would take around 10 minutes, full throttle, to get to 200-250 F, but this last time it skyrocketed almost immediately, then blew.

    There is no thermostat in it. There hasn't been for a while, apparently. That was the first thing I looked at, or for, and was astonished not to find it. There is a slight layer of rust all through out the coolant system, but nothing thats really obstructing flow, from what I can see.

  4. #4
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    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    Have you actually unbolted the risers and manifolds? Just looking at the hoses will tell you nothing about the condition of the riser and manifolds. If it only overheats at high rpm, it tells me its not getting enough water to cool the engine. So, I'd check that. It doesn't take long, maybe an hour or so. I'd buy new gaskets before you do though just so you don't reuse the old ones when putting it back together.

    It may also be a crack in the hose connecter on your drive. At low speeds its in the water, but at high speeds it sometimes isn't in the water and may be sucking up air instead of water. Again, not providing enough water to cool your engine.

    Oh, is it a raw water cooled engine or not?
    1994
    5.7 GI-PMDA
    AQ DP-C

  5. #5

    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    Sorry, its raw water cooled, sucking it directly from the lake. I disconnected the inlet hose from the water pump and flushed water backwards to the stern drive, and from what I could tell, nothing leaked out so it seems crack free.

    I know the basics of engines and am slowly applying it to boat ones, but I'd be lying if I didn't fully understand riser region. I'm not sure if all lay outs are the same, but I think you're talking about the part in the back of the engine, where the exhaust from the engine meets the outlet of the water and they both go down through the back of the boat correct?

    Either way, I unbolted the exhaust bellows and the housing above it and it all seemed clear. I then ran water down through the exhaust and it exited the boat cleanly enough.

    Any other thoughts? thanks for your help by the way.

  6. #6
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    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    Quote Originally Posted by clownchow8 View Post
    Sorry, its raw water cooled, sucking it directly from the lake. I disconnected the inlet hose from the water pump and flushed water backwards to the stern drive, and from what I could tell, nothing leaked out so it seems crack free.

    I know the basics of engines and am slowly applying it to boat ones, but I'd be lying if I didn't fully understand riser region. I'm not sure if all lay outs are the same, but I think you're talking about the part in the back of the engine, where the exhaust from the engine meets the outlet of the water and they both go down through the back of the boat correct?

    Either way, I unbolted the exhaust bellows and the housing above it and it all seemed clear. I then ran water down through the exhaust and it exited the boat cleanly enough.

    Any other thoughts? thanks for your help by the way.

    Flushing backwards from the raw water pump to the drive will tell you nothing about possible restrictions in the engine.

    In car terms, your manifolds are your headers. The risers will be bolted to them. Is that what you unbolted and looked at?
    1994
    5.7 GI-PMDA
    AQ DP-C

  7. #7
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    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    I found this on volvo's website. Part #1 should be your manifold and Part #22 is your riser. Is that what you unbolted and checked?

    I have a 5.7 and my engine set up is a bit different. I have two separate manifolds and risers.
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    1994
    5.7 GI-PMDA
    AQ DP-C

  8. #8

    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    Ok yeah. I unbolted the riser region and checked it out. It was clear and I ran water straight down through the exhaust. From what I can tell the inlet and outlet path for cooling water is clear. I think the issue lies within the engine block somewhere. The only problem is I don't know how to go about looking for it. I'd backflush that section of the coolant channels but I dont know how.

  9. #9
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    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    What about the manifold? If you say it doesn't have a thermostat, someone had to remove it. Maybe they did the same thing you did and just looked at the riser.

    At the end of the day it is your boat, so do what you feel is right. I would suggest draining the block then, a few times if necessary. I've done it after running through muck before. All it takes is removing the block drain plug.
    1994
    5.7 GI-PMDA
    AQ DP-C

  10. #10

    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    I'll definitely drain the block and clean out the muck. I'm new to boat engines so what I feel is right is slightly suggestive.

    What do you mean did the same to the riser region? How does that affect the riser region. You think maybe they removed something important from there aswell?

  11. #11
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    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    Quote Originally Posted by clownchow8 View Post

    What do you mean did the same to the riser region? How does that affect the riser region. You think maybe they removed something important from there aswell?
    I meant maybe they just took the riser off, like you did, to see if there was a restriction in there that could be causing the overheating instead of taking off BOTH the manifold and the riser. They're made of cast iron and do rust over time. If you don't want to spend the money in replacing them, I know there is a solution you can soak them in that will eat away at the rust. You'll have to search the archives on here to see what it is because I don't remember what it consists of.
    1994
    5.7 GI-PMDA
    AQ DP-C

  12. #12
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    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    I just thought of something else, assuming the manifolds and risers are in good working order, your impeller is in good shape, there is no restriction in the water intake at the drive, and you engine block is free of debris; what about the water circulating pump. The raw water pump, that the impeller sits in, just brings the water from the lake to the engine, but the engine's water circulating pump is what actually pumps the water through the engine.
    1994
    5.7 GI-PMDA
    AQ DP-C

  13. #13
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    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    Here is a little contraption I made to be able to troubleshoot issues in my driveway that may help you. I attach it to the raw water pump intake. The other end has a hose attachment that I screw my water hose into with a valve in the middle so I can cut off the water supply to the water pump when needed. The total cost of the supplies was about 10 dollars.
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    1994
    5.7 GI-PMDA
    AQ DP-C

  14. #14

    Default Re: Vovlo Penta 3.0 GS overheating and I don't know why

    I have the same engine 3.0gs with Cobra sx drive, began overheating and replaced all the hoses, impellar, and stat still no luck. Then removed the exhaust riser and found the flapper missing from the top of the exhaust. Removed the sink on the bottom of the exhaust at the leg and there was the burnt flapper valve plugging up the exhaust. Removed this and problem solved.
    FYI I could not duplicate the overheating with the muffs and garden hose as it is not recommended to run at high RPM.
    Boat is freshwater use only, 1999 engine and 185 hours.
    I did not replace the flapper valve as it would take quite the launch to make it work. apparently it is only a safety devise to prevent water entering the exhaust during a fast launch.

    Hope this helps someone out there , thanks to all for the other comments and experiences.

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