New 5.7 overheating

[Galvez83]

Folks i installed a new VP 5.7 in place of a 5.0gi. These items are new on the engine

Impeller
Circulation pump
Distributor
Ignition coil
Plugs and wires
160° Thermostat, oring, gasket and housing
Crankshaft pulley
Power steering pump
Starter
Fuel pump
Risers
MAP Sensor
Bellows & gimbal

Today i ran the engine inside the boat hooked up to the garden hose and lo and behold alarms went off overheating. I turned off to inspect. The IR gun confirmed 178-185 at engine. I took the boat to the marina and tested at the dock. Alarms again went off. I took the ir gun and pointed at several parts of the engine i got around 140 -160. I checked impeller and impeller is intact. Any ideas what in god's name to check next.

 

[Scott Danforth]

Water flow

Make sure you have water flow

 

[Galvez83]

Water flow

Make sure you have water flow

Scott, what should the riser temp be at idle IF running on muffs vs the sea?

 

[Scott Danforth]

no idea as it will be dependent on ambient temp, incoming water tamp and the angle of how your boat is sitting.

I know how much water flow you should have with either the F5B-9 or F6B-9 raw water pump.

how much water flow are you getting?

overheat is a direct sign of lack of water flow

 

[QBhoy]

Was it definitely a overheating alarm ?

 

[Galvez83]

Update, yes overheating. Verified water is circulating. Backflushed engine via the water hose that feeds the water pump. 2 findings so far. 1 is via the outdrive clean out port. Found a damaged bushing blocking the water circulation path. Cleared it and water flows easier now but still overheating. 2 disconnected both hoses that feed the exhaust manifold and started the engine. I found that via the water supply port to the left manifold is blowing exhaust gases. Manifold is shot and not only that the blow back causing back pressure on the rest of the engine. At least that is my assumption.

 

[Scott06]

Update, yes overheating. Verified water is circulating. Backflushed engine via the water hose that feeds the water pump. 2 findings so far. 1 is via the outdrive clean out port. Found a damaged bushing blocking the water circulation path. Cleared it and water flows easier now but still overheating. 2 disconnected both hoses that feed the exhaust manifold and started the engine. I found that via the water supply port to the left manifold is blowing exhaust gases. Manifold is shot and not only that the blow back causing back pressure on the rest of the engine. At least that is my assumption.

You are also likely getting some water into the cylinders this way

 

[dypcdiver]

" Found a damaged bushing blocking the water circulation path" was it a firm rubber bushing? If so possibly from the upper joint between the upper & lower parts of the out drive Part Number 3852315.

 

[Galvez83]

" Found a damaged bushing blocking the water circulation path" was it a firm rubber bushing? If so possibly from the upper joint between the upper & lower parts of the out drive Part Number 3852315.

It was pliable to a degree but very warped. It looked like a rubber anti back flow. I believe it is the part number you stated.

 

[dypcdiver]

If it is, then there is no other way to replace it other than splitting the upper and lower parts of the drive. Number 11

 

[Galvez83]

If it is, then there is no other way to replace it other than splitting the upper and lower parts of the drive. Number 11

Splitting won't be a problem. That i can do easy and might as well so i can inspect interior components. What has me more concerned is the overheating, while for less that a minute the damage that it might have done to a new long block.

 

[Donald0039]

You put in a new engine with an old exhaust manifold? Closed cooling or RWC? I assume RWC. Replace both manifolds. If you put any gasket sealer on manifold to riser gasket, less is better.

 

[Galvez83]

Yes both risers and manifolds have been replaced and still over heating. Good water circulation from the impeller to engine. Tested thermostat and indeed at 160 it opens. At this point i checked for clogs and i have come up empty. Tested today again and one of the new risers reaches 160° while the other is cool to the touch at about 110°. Both readings done with IR reader.

 

[Donald0039]

What brand and what outdrive?
Closed cooling or RWC?

 

[Galvez83]

Barr manifolds and risers, outdrive is a Dp-sm, RWC.

 

[Donald0039]

Does this setup have an impeller in the outdrive? Some do. Maybe only Mercruiser Alpha One.
You have have an oil cooler or PS cooler inline from outdrive water pickup to engine. Clogged?
Wrong manifold or riser gaskets that are blocking a water path and should not.
Too much sealer in exhaust manifold or riser gaskets.
Thermostat upside down.
Still a clog somewhere.

If sea water pump is on the engine then connect a garden hose right to the sea water pump intake.

 

[Lou C]

Are you sure both ports in the thermostat housing are open?
I have the same exhaust on my OMC Cobra and they run at approx 100* at idle and the most they get to is 135* after coming off plane. The starboard side tends to be a little warmer. 160 at idle is way hotter than normal.

 

[Donald0039]

Many marine engine have two thermostats available. A lower temp one for RWC especially in salt water. And a higher temp one for closed cooling.

 

[Lou C]

I think nearly all V/P engines used a 160 stat with the exception of the 454s which seemed to use a 140.
Even so the exhaust temps with the 160 will not be high if all is well because the exhaust should be getting full flow when the engine is cold, then when the stat opens, the warm water from the stat will flow through the exhaust.

 

[Galvez83]

Does this setup have an impeller in the outdrive? Some do. Maybe only Mercruiser Alpha One.
You have have an oil cooler or PS cooler inline from outdrive water pickup to engine. Clogged?
Wrong manifold or riser gaskets that are blocking a water path and should not.
Too much sealer in exhaust manifold or riser gaskets.
Thermostat upside down.
Still a clog somewhere.

If sea water pump is on the engine then connect a garden hose right to the sea water pump intake.

Impeller is engine mounted. I checked the PS cooler before install and is clear. Today i did the clear hose test. My findings where limited due to family time. What i found out was that i noyice the incoming water into impeller housing coming in with much air.....a lot. I will check with a water hose directly to the pump to test if still overheating.