Blown circulating pump pipe after thermostat replacement

[Rudolf Opperman]

Good day

I have a Volvo Penta 5.7 GXi-H with SX-A stern drive. I recently replaced the exhaust manifold and overhauled the sterndrive (new bellows, universal shaft and new bearings) and did a major service, new impeller, new plugs, new belts, oil and filters. I took the boat out after the repairs and it ran like a dream. I then noticed the temp is running very low and presumed the thermostat was stuck open. I replaced the tested thermostat and took it back to the water. thereafter I blew the U shaped hose between the thermostat housing and the circulating pump, replaced and tested agin to only blow up once again. I then removed the thermostat and the boat is running perfectly fine again but obviously it runs too cold. Ive checked all of the hoses for blockages, If I connect the boat to a hose and run it it seems to be fine and the water is coming out of the exhaust as per before. any advise????

 

[Bondo]

Ayuh,...... Welcome Aboard,...... Any chance you put the t-stat in upside-down,..??

 

[Rudolf Opperman]

Thanks for the welcome. I also thought I might have done that buy according to the workshop manual it is fitted correctly?

 

[Lou C]

when you hold the stat housing in its normal position the spring should face down. If you put it in upside down I'd think the engine would have overheated. Are you sure its the right stat? Also is the little bypass port open? Make sure it is as well as the 2 ports that feed the manifolds...

 

[Rudolf Opperman]

Boat has not overheated and stat is definitely not upside down. Ive checked the bypass port and the water is flowing freely on the T section which feeds water to the manifolds

 

[Rudolf Opperman]

Boat has not overheated and stat is definitely not upside down. Ive checked the bypass port and the water is flowing freely on the T section which feeds water to the manifolds. The stat is also OEM part and matching the old one

 

[Rudolf Opperman]

Good day guys after some more investigation I believe to have found the problem. The Thermostat housing has a bypass port, it seemed to be okay but after poking a screwdriver in the port and giving the housing a decent acid dip it opened completely. I did a high pressure clean inside the housing and reassembled everything. Tested with a hose and all seems to be okay. I will obviously only know once the boat is back on the water. Will update once done. Thanx for the advise. Much appreciated here from South Africa.

 

[Lou C]

If you are in salt water or corrosive fresh water I would replace those thermostat housings just the same as when you replace exhaust elbows/manifolds. I’m on my third set of both. Every 6 years or so here in Long Island NY. The OMC Cobra style thermostat housing and exhaust design was picked up by Volvo after they bought out OMC. So the designs are nearly identical except for the impeller.

 

[Rudolf Opperman]

Lou C Thanx for the advise. Will definitely order a new one after all this Lockdown drama has blown over and things are back to normal. Any decent websites you could recommend to buy online and import myself? These type of spares are not widely available here and if you do get they are very overpriced. TIA

 

[Lou C]

On this site there is a link to the Volvo Penta on line catalog. The last one I bought was about $100-120 USD. We are not allowed to post competing websites here but these were used for many years and should be widely available. Just get the VP parts # and do a search. Even amazon or eBay....

 

[Rudolf Opperman]

Thanks a lot

 

[Lou C]

http://www.volvopentastore.com/Circu...view_id.773558

part #1, I see they went up in price since the last one I bought...this is OE...
I'm pretty sure GLM makes a copy of this part (aftermarket) but their quality reputation is not the best. BTW, Barr makes a nice aftermarket exhaust for OMCs and Volvos. I used their stuff on my OMC which originally came with the one piece V6 exhaust manifolds, these long ago became NLA, so I converted to the later style. Have to replace exhaust every 5-7 years here in salt water. The BARR kit is a lot less expensive than Volvo OE.