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pkula

2004 Volvo Penta Thermostat Replacement

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I recently purchased a 2004 Signature 310 with dual Volvo Penta 5.0Gxi-E engines. The prior owner removed the thermostats and gave me replacements to put back in but they appear to be smaller than the opening in the thermostat housing. The replacements are correct according to the manual (P/N: 3862835), but they are about 1/2" smaller in diameter than the opening in the lower section of the housing. Normal installation tells me the thermostat sits in top of the lower Thermostat housing at the opening. The prior owner said these thermostats are correct and that an O-Ring holes them up inside the "top section" of the thermostat housing but I cannot see how this can be. Has anyone run into this and is there something I am missing? Thank you for your help!

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That is correct. There is a small groove in the housing the o ring sits in. The thermostat slides in and the o ring keeps it in place. 

The bigger question is why did he remove the thermostats in the first place? Overheating issues? May want to do some thorough checking.

sounds like a new boat to you. Did you do a sea trial and have a survey done?

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Thank you osteodoc08! This is what the prior owner said, but it was not intuitive to me. This is my first Volvo Penta as I have had Mercs all my life and replaced many thermostats. According to the owner (after i bought the boat) he said, oh by the way you need to put these thermostats in. He stated he was changing out everything that could fail prior to selling me the boat. He didn't say anything about overheating, just preventative maintenance. Actually when I bought it, it was not for sale, but when he heard I was in the market, he said it "could be for sale". Anyway, we put together a deal and I now own the boat. According to him when he removed the thermostats, the replacements his dealer sold him were not the right ones so he left them out until he got the proper ones. Sounds a bit fishy to me in hindsight. I sea trialed the boat and have run it twice since for short periods and had no issues with overheating etc. If I would have know there were no thermostats installed, i would never have run it. Anyway, it ran fine without the thermostats, but once I learned of them not installed I have not run the boat. I'm hoping I will not find the boat has an overheating issue once the thermostats are installed. Actually the boat only has 249 hours and is in mint condition. It fires right up etc. The price was right too. - Thanks again!

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his story seems plausible.  I would replace them and go from there.  While your there I would just go ahead and replace the impellers as well, that way you have a known point in time for them.  They should last 3-5 years.

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Thanks soldier4402, I will go ahead and replace them like you said, I was thinking the same thing. He did just replace the impellers as well so I have a good starting point. He gave me the old ones and they were in good shape. Appreciate all the good info!

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NP.  I get a new boat I always replace impellers and lube/filters right away unless I can verify otherwise.  Not that I don't trust the past people, it just gives me a known point for me to work off of.  Depending on age of boat without known history, I would also inspect plugs/wires cap and rotor and replace if necessary

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Thanks again soldier4402. 10-4 on the lube, filters, cap/rotor, plugs etc. I have done all that as well. Other than the thermostats, all systems go. I always follow the same replacement strategy as you. While we are talking, do you know of a good way to check the outdrive lube while the boat is in the water? On Mercs there is a reservoir in the engine room, but on a Volvo you check via a dipstick in the top of the drive. That is a bit precarious. 

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10 minutes ago, pkula said:

Thanks again soldier4402. 10-4 on the lube, filters, cap/rotor, plugs etc. I have done all that as well. Other than the thermostats, all systems go. I always follow the same replacement strategy as you. While we are talking, do you know of a good way to check the outdrive lube while the boat is in the water? On Mercs there is a reservoir in the engine room, but on a Volvo you check via a dipstick in the top of the drive. That is a bit precarious. 

yup the dipstick is the only way.  Typically its an item to check periodically.

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Thanks soldier4402, that's what I thought. Would be best to check on the trailer. I know my other merc uses a good bit of lube so this should be a routine thing.

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You can check it when the boat is out of the water. Just lower the drive and make it level. Inspect the O ring and make sure it’s not nicked or cut. Don’t overtighten either. 

 There is an inside reservoir for the hydraulic tilt. 

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Thanks for the info osteodoc08. I will have to wait to put it on the trailer. Sounds like Volvo missed the boat on this design.

 

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