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| 7.4Gi overheat & loss of oil pressure https://www.smwebhead.com/phpBB3/viewtopic.php?f=11&t=15003 |
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| Author: | rpengr [ Wed Aug 03, 2016 8:02 am ] |
| Post subject: | Re: 7.4Gi overheat & loss of oil pressure - FOLLOW-UP & CLOS |
Alumin8 wrote: One lingering thing thought is using my IR gun, the port side exhaust manifold (casting) is usually 30 Deg cooler than the starboard.. I'm not sure if this is indicative of a partial plugging of the starboard riser or not - or whether it's worth digging into yet this summer.. This can be caused by rust buildup in the thermostat housing...specifically in the two outlets where the hoses connect to the manifolds. My Horizon is also a 2000, and about 3 years ago I used a drill to open up the two outlets due to some rust buildup. I don't remember the exact size of the drill I chose, but I think it was close to 7/16". I will probably replace it within the next year. As you said, it could also be in the manifold, but it is easier to start with the thermostat housing. |
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| Author: | LouC [ Wed Aug 03, 2016 10:50 am ] |
| Post subject: | Re: 7.4Gi overheat & loss of oil pressure |
On many Mercruisers it is common for the starboard side manifold to run hotter. On my OMC which uses the exact same thermostat housing as many Volvo engines, the starboard side runs a tiny bit hotter (maybe 10*) usually at idle they are both at 90-100*F, the hottest they get after coming off plane is about 135*F. Yes the passages in the 'stat housing can neck down due to corrosion, I have found that you can ream them out but in salt water it gets to a point where there is enough flaking rust that its better to replace it. What temps are you getting on the risers at idle, and after coming back to idle after coming off plane? |
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