cant' get up to operating temp.!!

[Joesailboater]

I can't get up to operiting temperature.

I can only get to about 80 degrees. My first thought was that my gauge was bad but after I shut down it climbs to 140., of course there is no cooling water going throught the head then. After running the motor for at least 30 minutes, the block, head, manifold, exhaust are all just "warm" to the touch. I have let the motor run in the slip for 30 minutes and ran it against the docklines for about 10 minutes but I can still keep my hand on all the engine parts when it's running. I am near Annapolis so the water temp is not too cold yet. 55-60 maybe.

I just installed a new MMI water pump, a new cooling system bypass kit, new fittings and hoses along with a new raw water stariner.(first for this boat...1974 Newport) I also made sure all the passages that I could reach are clear and open while I had everything appart.

So here's the story,
While preparing to motor out the other day, I was warming the motor and watching the temperature gauge. It just kept climbing and after a quick run to the transom, (nothing but steam comming out) I realized that I had a boackage in the cooling water system. (Hence the newly installed strainer.)
The operating temps had been climbing a bit during the season but never got above 180. I was glad that I was watching the gauge because it shot up over 190 before I shut her down.

So.....Is it the new check valve? I have the old Holly thermostat and it works fine but that shouldn't keep the thing from getting up to temp anyway.

[hanleyclifford]

Is this FWC or raw water cooling?

[Joesailboater]

This is a raw water cooled system. Now that I read a little more, I think that maybe the sending unit itself may be blocked. When I cleaned out the gunk under the thermostat housing I may have pushed something sown there. I was preparing to do an acid flush after all this but I think I should figure out why the temp stays so low.

The only part of the whole thing that gets the least bit warm to the touch is the very front, bottom part of the mainfold.

[hanleyclifford]

Now that you have the bypass kit with the valve you have a powerful tool to regulate temp. To maximize thermostat ability to raise engine temp the valve should be left wide open.

[JOHN COOKSON]

Blocked Sending Unit

Joe

You may be able to blow crud away from the temp sending unit area by:

Removing the sending unit and substituting a nipple in it's place. Attach a hose to the nipple and clamp it. Run the engine untill it gets up to operating temp, clamp the bypass hose and unclamp the hose on the nipple.

Hope this helps.

TRUE GRIT

[Joesailboater]

John,

I will remove the sending unit in the morning and try to clean in there as much as I can but the nipple idea sounds promising. As far as I can tell, the engine just won't warm up to operating temp.

Hanley,

I have the valve open all the way on the bypass kit and the temp just wont get up there. The thermostat has been removed all together in preparation for an acid flush. I also thought that no water was getting to the thermostat housing but that's not the case. I didn't use gasket sealer and I have a little seepage at the base of the housing. I'll seal it all up after the acid treatment and fresh water flush. I would think that even if all the cooling water entered the block that I would still get up to operating temp.

I would welcome the lower temperatures but I don't think that running that cool is very good for the drive components because the oil doesn't achieve it's proper viscosity.

I still think there may be a blockage preventing the heated water from getting to the sending unit but that won't explain the fact that the motor remains almost cool to the touch after running for 30 minutes. Like I said earlier, the temperature gauge rises to 140 after I shut down and the cooling water stops circulating.

[hanleyclifford]

I think I misunderstood. If you have no thermostat in the engine then your condition is quite normal. Raw water engines without a thermostat can run very cold. When you replace the thermostat make sure the housing is in good condition specially the machined "seat". If you are getting good discharge water flow I don't think you have a problem at all.

[Joesailboater]

Thanks,

I'll proceed with the acid flush tomorrow and replace the thermostat after. I'll let you know how it behaves when it's all back together.

[sastanley]

JSB, i've experienced similar issues as the Chesapeake bay water cools off (i.e., not getting up to operating temp)...the engine temp stays cold..especially if you are running with no t-stat...and then the numbers go up when you shut down.

I'll be in the Annapolis area on Sunday. I am racing with the Pirates Cove Yacht Club out of Galesville in their Frostbite series. The boat I am racing on is way up the Rhode River (Mayo, Rt 214, dock time is 11:30).)...if I need to make time to visit your boat as another Atomic 4 enthusiast prior to racing, I'd be happy to.

Send me a message thru the forum...I'll be driving up there for a few more weeks. I am no expert at anything, but I'll be happy to stick my nose in it!
-Shawn

[Dave Neptune]

Temp!

Joe, I have been running without a thermastat for 26 years now and no problems. My engine idles at around 100~120 after about 15~20 minutes at around 1100 rpms (warm up and a bit of re-charging of the batteries). I am in about the same temp water 60~65 and raw water cooled. I have a gut feeling that you may have a blockage at the "Tee" fitting which has a diverter on the inside of the block. Or possibly the diverter has been removed by a PO, worth checking.
As you close the valve more water is forced into the block and the diverter is necessary to push the water to the back of the block for good cooling. Try closing the valve completely and check to see if it affects the amount of water being pumped out the exhaust, less would indicate that the diverter may be blocked a bit.
I cruise at 2000 rpm and about 135 degrees and have done so for a over a quarter of a century. I have acid flushed my block 3 times now and it will be due again in the next couple of years.
I have found that running without the t-stat can affect the temp of the sending unit a bit as when the valve is open enough cold water is flowing in the area of the sender to cool it a bit more than the block temp. When I shut down I get a rise in temp if I turn the ign. back on of about 10~15 degrees and that is normal on almost any application.
IMPORTANT~~I would seal the t-stat housing before doing the flush so the acid won't make the gap any bigger and more difficult to seal. Use permatex Aviation there and not silicone or RTV.

Good Luck
Dave Neptune

[ndutton]

I cruise in the same waters as Dave, have what has been referred to as the Holy Grail of thermostats, the Holley 3 spring, raw water cooled, no bypass system, acid flushed 2 years ago, rinsed internally with fresh water after each use.

My engine runs between 140 and 160, temp varies directly with rpm and load.

[Joesailboater]

Well I got it all back together and did the acid flush. Nothing remarkable came out that I could see. Just a little crud. Replaced the thermostat (Holly three spring) and sealed up the the housing with Permatex and torqued it down. No leaks. I ran several 5 gallon buckets of fresh water in through the "T" fitting both with the bypass ball valve open and closed. No difference in the amount of discharge or the rate of take-up from the bucket so the diverter would seem to be clear of obstruction.

I was a bit surprised at how fast the water was taken up from the bucket though. 5 gallons in about a minute or so. My new MMI pump really works great!

I ran the motor for about an hour after that and she still only gets to about 90 degrees.

I think I may pull the check valve off of the bypass system and see if that lets it get up to operating temperature. It's either getting too much cooling water into the block all the time or I have a faulty gauge or....it just runs cool with the raw water temperature being what it is here in the Annapolis area this time of year. The block stays basically just warm to the touch front and back.

Should I worry? Or go on to the next project!!

[hanleyclifford]

Most owners get the bypass kit because they are running too hot and want to close the bypass. In your case I believe the kit may be counterproductive. Even in the wide open position the valve is a constriction, actually partialy closing the bypass loop. That new Moyer pump (the best in the business) coupled with your clean system, and that bypass "valve" (actually a 1/4" "venturi") means your system is really efficient. I suggest eliminating the bypass kit. The valve makes a good fuel shut off.

[Joesailboater]

Hanley,
I think you are right. With the addition of the hard angle of the new brass fitting, the check valve and the 1/4 opening in the ball valve, the water is restricted enough that it pushes into the block too much. I wonder if eliminating the check valve and/or installing a larger ball valve would work. I thought that ball valve looked a bit small.

I just need to try the different combinations until I get what I want.

[keelcooler]

Sure sounds like a sender or gauge issue to me. I just can’t get my head around a internal combustion engine running cooler than 110 even on a cold day in March.

Duck tape a meat thermometer on the transom exhaust water discharge after warm up to test.