Engine overheat can't identify thermoasat look at photo.

Hey guys I had problems with the engine overheating last time I took it out so I decided to change the impeller check the thermostat and do a complete circulation check to make sure everything was working ok but I can't seem to identify the thermostat to inspect it.

Is it located inside the part where I circled in white? or is it the two other colors?

Could someone identify all 3 parts while were at it? By witch one should I start? Is one more prone to cause problems then the other?

I have a 1997 volvo 7.4 GI/DP it has a Model # 74FGPLKD that I can't find on the volvo site BTW?????

Could someone confirm the the thermostat should open at 170 degrees?



Here is my old impeller installed that has now been replaced. Once I got it out of there it didn't look so bad.



I also had a little surprise when I opened up the gear oil dipstick. There was still pressure in the gearbox 48 hours after we used it so I'm guessing it was only humidity the milked it up and not a major seal leak. There was no water inside the foot and I have seen some pretty worse looking oil so I am hoping new oil will be all it takes.



As always guys thanks for the input

Your engine thermostat is inside of the housing circled in white.

The engine temperature sender is the one in the intake manifold..... that is where your gauge receives temp data.

The temp sender that is installed in your suction side of the engine circulating pump is perhaps there simply as a plug...... probably in lieu of a correct brass plug.

If in lake/river water, the 170* stat can be used.... see your OEM manual.
If in salt water, again, see your OEM manual. Very likely it will require a 145* stat due to salt crystallization.

Your drive oil is milky, which indicates water instrusion.
Best have the drive re-sealed, followed by a pressure/vacuum leak-down test.

.

RicardoMarine said:

Your engine thermostat is inside of the housing circled in white.

The engine temperature sender is the one in the intake manifold..... that is where your gauge receives temp data.

The temp sender that is installed in your suction side of the engine circulating pump is perhaps there simply as a plug...... probably in lieu of a correct brass plug.

If in lake/river water, the 170* stat can be used.... see your OEM manual.
If in salt water, again, see your OEM manual. Very likely it will require a 145* stat due to salt crystallization.

Your drive oil is milky, which indicates water instrusion.
Best have the drive re-sealed, followed by a pressure/vacuum leak-down test.

.

Click to expand...

Anyone have a good spot to get one of those leak down test machines for volvo drives?

I went to this guys' web site and bought the tester for both pressure and vacuum. http://cgi.ebay.com/ebaymotors/Volv...at_Parts_Accessories_Gear&hash=item414fb01bc1
If you've got all the parts laying around, you could probably make one yourself.

RicardoMarine said:

Your engine thermostat is inside of the housing circled in white.

The engine temperature sender is the one in the intake manifold..... that is where your gauge receives temp data.

The temp sender that is installed in your suction side of the engine circulating pump is perhaps there simply as a plug...... probably in lieu of a correct brass plug.

If in lake/river water, the 170* stat can be used.... see your OEM manual.
If in salt water, again, see your OEM manual. Very likely it will require a 145* stat due to salt crystallization.

Your drive oil is milky, which indicates water instrusion.
Best have the drive re-sealed, followed by a pressure/vacuum leak-down test.

.

Click to expand...

Took off the thermostat housing to check the thermostat and there is nothing in there?

If there is no thermostat in there shouldn't it be running cold all the time?

I really don't know anymore...... Will have to identify the 2 other things that look like thermostats.

Unless the gauges are defective?

Youmay want to check with an infrared thermometer the engine exhaust manifolds temperature. If significantly lower than the gauge indication, you may have a gauge or a sender problem.

If the infrared thermometer confirms the temperature gauge reading, then you could have a worn circulating pump or choked cooling passages in the exhaust manifolds/risers, or an air ingress between the outdrive and the raw water pump.

In any case, I would replace the thermostat.

RicardoMarine said:

Your engine thermostat is inside of the housing circled in white.

The engine temperature sender is the one in the intake manifold..... that is where your gauge receives temp data.

The temp sender that is installed in your suction side of the engine circulating pump is perhaps there simply as a plug...... probably in lieu of a correct brass plug.

If in lake/river water, the 170* stat can be used.... see your OEM manual.
If in salt water, again, see your OEM manual. Very likely it will require a 145* stat due to salt crystallization.

Your drive oil is milky, which indicates water instrusion.
Best have the drive re-sealed, followed by a pressure/vacuum leak-down test.

.

Click to expand...

I also just realized that the top hoses on the thermostat housing have been bypassed to my water heater.

Is that the way to go or not?

The yellow is going to the port manifold and the yellow runs to the water heater and then from the water heater to the starboard side manifold.