No Thermostat? What...

[Oaktown27]

Hi all, new to the forum, and so happy to have found it. I picked up a '72 Santana 27 during Covid to keep my sanity. The Atomic Four was running and a bit of a mystery to me on how it operated (first A4). Fast forward to November, taking it out of the dock I realized that when increasing power the engine bogged down and sputtered. I returned to the dock and started the process of figuring out the A4.

So, did a tune up, new plugs/points/distributor. Fired it up, and still had the same problem. The engine started to blow white smoke, which I think was steam based on several other posts. Shut it down.

Returned with a compression tester to see if I had a valve problem. I started the engine (started right up) and the smoking was gone. shut it off, and realized that the motor was running hot. I could not due the compression test, but noticed a leak on the Thermostat cover. Started up the engine and didn't seem to see any raw water cooling coming out.

Now am assuming I have a cooling problem. Think my intake might be clogged, but also wanted to replace the gasket on the thermostat cover. Took off the cover and whoa, not thermostat. I do see that some run with out one, but I do not think there is a bypass valve set up. Not sure if I know one if I saw one.

Since I had this apart, decided to pull the impeller as well. No water came out when I pulled the plate and pulled the impeller.

So, should I put a thermostat back into this?
Do you think the lack of cooling was a cause of power loss?
I hate to think I was running it with out cooling.

Looking for some guidance/ideas.

Also, it does have a Sierra 18-7844 fuel filter. I picked up a replacement, but have yet to install it. Figured I need to solve my cooling first.

And the gauges don't work (another project)

[Dave Neptune]

First welcome to the MMI Afourian Forum.

Lets talk cooling first off. Don't worry about the t-stat just yet!! You state that no water drained out of the pump when the cover was removed, was the water valve feeding it on the thru-hull open?
Next when it was running was water coming out the exhaust?

To find the bypass valve~~follow the line from the pump to the "Tee fitting" on the side of the block below the alternator. The line should connect to the tee and another line will go from there to the "t-stat housing" and in this line should be a valve, the bypass valve. When the valve is closed all of the water from the pump is forced through the block for maximum cooling. The valve is adjusted open until the running temp of 120~140* is achieved, opening the valve allows water to "bypass" the block thus causing the engine to run warmer due to less water.

You did a tune up now don't touch anything but do check to see if the C-advance is operating. To do so just remove the dist cap and give the rotor a twist. It should rotate a bit and when released it should snap back. It does need to work for proper running.

RE fuel go ahead and replace the filter and check all of the fuel line connections from the tank to the carb to be sure they are tight.

It would also be a good idea to do a dry compression test and then a wet one. Test with all of the plugs removed and the throttle wide open, Do each cylinder twice and record your findings, Then spray some oil (WD-40) into the cylinders and test again twice on each cylinder. Do give a little spritz to the cylinder being tested when testing. Again record your results.

Get some answers for us and the diagnosis can begin.

Dave Neptune

[Oaktown27]

Thanks Dave for the guidance. Truely appreciate it.

The through hull valve was open as I closed it when I pulled the pump cover. Was interesting as I see these typically have an o-ring or gasket, but mine did not.

Separately, when I did the tune up, I did take the plate off that holds the points/condenser, and tested the advance springs (tip on the MM video). They seemed to be in working order, but will test as you suggest.

A bit rainy here in the bay area, so wont be able to do the compression test for a few days, but will report back.

I did not recall seeing a valve on the water intake past the T, but wasn't looking for it either.

Update in a few days.

Happy New Year!
Pete

[Al Schober]

I wouldn't worry too much about the lack of a thermostat. I ran my engine for years without one. A photo of the alternator/starter side of your engine would help us to see what you have.
In the later years I had my engine I converted to a heat exchanger system with glycol cooling. Highly recommended. It worked so well that I was considering re-installing a thermostat (180F) and using all that heat to heat water - add hot water to the boat. Never got there.

[Easy Rider]

Re the overheating problem. The first thing I would do is check the through hull valve to see that it is not plugged. Disconnect the intake hose from the through hull valve and then open it up. You should get a good flow if no restrictions are in the through hull. I would also remove the outlet fitting at the aft end of the manifold and check for being plugged. These in my opinion are the simplest things to check and known problem areas. Also, you might need to prime the system to get it pumping. In my boat I have to always prime the cooling system after any impellor replacement.

[joe_db]

Originally Posted by Easy Rider

Re the overheating problem. The first thing I would do is check the through hull valve to see that it is not plugged. Disconnect the intake hose from the through hull valve and then open it up. You should get a good flow if no restrictions are in the through hull. I would also remove the outlet fitting at the aft end of the manifold and check for being plugged. These in my opinion are the simplest things to check and known problem areas. Also, you might need to prime the system to get it pumping. In my boat I have to always prime the cooling system after any impellor replacement.

Do this first!
Water needs to make it to the pump or no other fix will help.