Engine never warms up

[olebiker]

I searched but couldn't find an answer.
My motor never warms up. New water pump, newly flushed, new thermostat. Tried adjusting the bypass valve to every conceivable location. The needle hardly moves and there is no steam out the exhaust. The hose from the thermostat housing to front of the manifold remains cold. Great water flow out the exhaust.
Any ideas?

[ILikeRust]

How long did you let it run with the bypass valve fully open?

[JOHN COOKSON]

Are you sure the new theromstat works?

TRUE GRIT

[olebiker]

Ran the motor for an hour in every conceivable position including bypass valve fully open. Tested the thermostat before installation, opened at about 160 and closed when cool.

[romantic comedy]

That new cam shoe has the water flowing so well that it wont warm up.

What temp did it run at before?

[JOHN COOKSON]

Try getting rid of the valve on the bypass hose and run a straight hose in its place. Apparently the valve itself, even when fully open, is providing to much restriction. Rebuilding the water pump and the flush has changed the water flow dynamics.

TRUE GRIT

[ndutton]

You didn't say but I'm assuming the engine is raw water cooled. Mine was the same way when it was RWC, the gauge barely moved off the cold peg. I'm sure the engine thought I was running off the northern coast of Siberia or sumthin'.

If you're RWC and running in salt water you don't want to get to 160°. Salt crystals start forming at that temp clogging things up.

[Marian Claire]

FWIW. I had a brand new T-stat that functioned perfectly in a pan test but when installed it would either stick open or closed. My solution was to leave out the T-stat and add a recirculating loop giving me control over operating temp under all conditions. Works for both FWC or RWC. Dan S/V Marian Claire

[Dave Neptune]

2 things first?

First are you sure you are using the correct t'stat with the bypass?
Second check the valve to confirm it is opening and closing! Let us know the type and size to if possible.

If the above are correct check the gage, remove the sensor and hook it up in a shallow pan of boiling water and have a thermometer at the ready.

I run without a t'stat in So Cal and run at 130~140 at cruise 2200/with my Indigo prop. You are in a bit cooler water and after you have confirmed the bypass valve and t'stat are correct and the gage is functioning it will be time to look at the volume of water (the shoe).

Dave Neptune

[tenders]

Sounds like you've got two things going on: why isn't the engine warming up as you expect, and why isn't the bypass valve doing anything perceptible. They may or may not have the same cause.

I'm guessing the thermostat isn't seated squarely, so it's letting water through. Could it be mounted upside down?

Is it possible you have a restriction immediately after the bypass, so whether the bypass valve is open or closed, water isn't flowing through it?

My boat doesn't have a bypass valve, nor a thermostat, and I deliberately put a bolt into the bypass hose so most of the water flows through the head specifically to keep it very cool. This wasn't my idea, but I like it a lot and it's served me well since the rebuild 20 years ago.

[dvd]

Ole

I don't think you told us whether you ran it under load away from the dock. If it just sitting at the dock even ifyou have it in gear tied to the dock it won't warm up much. Especially this time of year with the cold water temps. If you haven't already done this take the boat out and run it reasonably hard for a while. It should warm up fine.

dvd

[olebiker]

Motored the boat yesterday for an hour with the bypass valve fully open. No change, check the flow through the hose to the tstat to ensure no blockage=OK, Tstat is MMI single stage with spacer installed with the tstat flange against the head and spring mechanism down, all hoses on this side are 1/2" with 3/8" pipe size fittings with 1/2" barbs, I remove the check valve between the t fitting and bypass valve thinking it could be creating too much back pressure. Tested the heat sensor=OK. Getting a huge amount of water flow. The water pump is MMI's with no cam shoe. The housing is cast a bit flatter where the cam shoe used to be. After running for an hour, the hose from the tstat to manifold is cold as well as the manifold itself.

[ndutton]

Ain't it fun spendin' other people's money

In my opinion the very best thing you could do is go to fresh water cooling. You'll get the temperature you want plus do your engine a world of good over the long term all in a single upgrade. The money you spend today will save you later by avoiding casting replacements, the manifold in particular.

Back to your report though, I'm conflicted. Cold water entering the manifold suggests it's not flowing through the block and picking up heat. The conflict is your gauge says otherwise. Can you determine if the distributor side of the block is getting warm or hot? Do you have a non-contact infrared thermometer to measure the block temp?

[romantic comedy]

I did not know the pump would pump with out a shoe.

I guess making your own bypass for the water flowing from the pump would be the next step

[Marian Claire]

I am assuming RWC. A simple test would be to put a valve in the line that exits the manifold and ties to the wet/dry connection. Close it 30%, 50%, 70% and see what you get. It will simply slow down and reduce the volume passing thru the whole system. The pump should have no issue with the extra head pressure. I used this method before setting up the recirculation loop. Dan S/V Marian Claire