No Thermostat? What...
 

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)

Info needed
 

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 :cool:

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

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.

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.

Compression Test done. Waiting on parts.
 

Thanks. I do have a feeling the intake might be plugged, so will take the suggested approach by taking off the intake hose.

I have had this for two years, so the maintenance is needed as I didn't get any history. I did to a compression check as well. Done while cold since I pulled the impeller and the thermostat cover.

Dry/With a spray of WD

Cyl 1 80/100
Cyl 2 100/100
Cyl 3 85/90
Cyl 4 95/100

Not my expertise, but seems in tolerance?

Also followed the hose back to the T, no valve there.

Also the advance test worked by twisting the rotor test.

Waiting on parts, so I can replace the gasket, the impeller, and put in a MM pressure/temp gage on the head where the sender unit is.

Thanks All.

The compression numbers look OK, nothing to be concerned with.

You can install a 3/8 gate valve in the "bypass line" with little effort. You can use slip fittings or pipe to attach to the t-stat cover, either way works. Just do it the easiest way for operation.

If you crack the "water valve" on the thru-hull does water gush to the pump? Follow the line to see if there is a strainer in the line or the thru-hull may be plugged too if no flow.

Was there a line from the Tee fitting to the t-stat housing? Just want to confirm there is for a bypass valve.

A good idea as you got hot is to check under the exit fitting on the manifold. This is a spot that can collect debris (especially if there is no strainer on the intake side of the pump) and cause flow restrictions.

Dave Neptune :cool:

Progress Update
 

Appreciate the help to date. Now that California has dried out a bit I have finished a bunch of other maintenance.

Put in a bypass valve and replaced the impeller.
Scraped the hull near the intake to clear any blockage.
Confirmed I have flow and the cooling issue is resolved!

I still have a power issue. After starting up the motor, applying more power continues to cause the motor to "bogg down" and hesitate. Interestingly, when I reapplied the choke when this was happening the engine came back to life. I am thinking this is a sign of a fuel problem. Think a carb clean is next? I did replace the fuel filter. Thoughts?

Also notice my exhaust riser was damp and under further investigation, pulled the heat wrap off and this is totally rusted with a split in it. I think I have seen home grown solutions and that MM sells this. Any thoughts on the best route here?

Thanks
Pete

Pete, I would get the exhaust fixed as it is now a known problem. The exhaust if old enough to crack and leak could very well be "plugged up" which is a common cause of bogging and loss of power. Most exhausts are cobbled from "black pipe" fittings available at most hardware stores.

Once the exhaust has been addressed and if she still bogs down, then it will be time to look at fuel delivery and/or the carb being plugged up too. The increase in performance of engaging the choke is a good indicator of a lean fuel delivery issue which can be caused by a few things in the fuel system.

Dave Neptune :cool:

I suspect your exhaust may be the problem. Fix that, then if applying the choke keeps it from bogging down, you are running too lean. This could be from a lack of fuel flow, a common problem. Having a fuel pressure gauge just before the carburetor can tell you if the fuel flow is restricted. If so, it could be junk in the fuel filters, or the main jet, or the idle jet. So, cleaning and inspecting the carb jets is a good idea, especially if you haven't done it lately. Replace filters at the same time. You may also be running too lean because of an air leak around the carburetor gaskets. Your idle screw may be turned out too far; it should be around 1 turn out from the seat. If you have an adjustable main jet, turning it in to the seat and back out 1.5 turns may dislodge some crud there.
Open up the distributor cap and make sure the rotor snaps back easily when you turn it clockwise. If not, the flyweights under the breaker plate will need to be cleaned and lubricated. Once it is running, turn the distributor to get good timing, as having the timing too advanced (ctr. clockwise) can also make it run too lean, as I understand it.

Is the bogging happening when the engine is in gear? Let’s not forget that a dirty prop can cause a lot of symptoms that seem like engine problems.

Riser making is a chore we all do. I use black iron 1-1/4" plumbing from the local store plus a Moyer flange. There are a ton of threads on this.
Tell use what diameter hose you have for the exhaust and how far up you can go vertically from the exhaust manifold and we can provide some suggestions.
Moyer has various bits to help. I have taken to getting a stainless hose to pipe adapter, the cheap way of using an iron close nipple always seemed to end like the photo shows.
Also note if the DRY section is rusting out, you have problems!

Try https://www.moyermarineforum.com/for...ht=build+riser

Black Pipe or Galvanized.
 

I am building a new hot section. I have seen both Galvanized used and black pile. Was leaning toward black pipe, but getting the sections are/will be a chore.

Is Black Pipe the way to go?

Also, did not have an anti-siphon, so also have a Marlon on its was as well.

Thanks
Pete

Galvanized pipe gives off nasty fumes for a time that can actually make you sick. Use the black pipe.
* it is actually called zinc fever https://en.wikipedia.org/wiki/Metal_fume_fever

Finished building the hot exhaust riser. Thanks to the local Grainger as it seems black pipe is not a stocked item any more at the local plumbing shop.

Pulled the carburetor, and plan to clean the jets as suggested. I wasn't planning on rebuilding the carb with new jets and only going to clean it up. Hate to spend 100 bucks on the kit if I don't need to. Any thoughts on this?

Still need to drain the fuel pump sediment bowl and check the screen.

Also, I don't have a scavenge tube installed. Looks like the hole in the manifold is plugged. I assume I should reinstall one?

Feels like I am almost there, and do say the A4 is looking (and starting) much better than it was.

Thanks

Yes the scavenge tube is important as a safety factor and adding air for idle purposes. It is just plain ole 1/8 copper tubing with a 1/8"NPT adaptor for installation.

Dave Neptune :cool:

Oaktown Pete, welcome! Great job methodically attacking one issue at a time. We'll help you get her running great again!!
Sometimes we preach around here that when you tackle too many issues at one time, you can't always figure out what was actually causing the problem in the first place, but you're doing it the right way IMO. :)

Happy Ending
 

Happy to report that after pulling the carb and cleaning the jets, cleaning the pump bowl and adding the scavenge tube, power has been restored!

Thanks to all for the support and suggestions. Have to say, was a bit intimated when I started on this, but know have built up familiarity and confidence with the A4.

Only thing left is to adjust the reverse, which seems fairly straight forward.

Couldn't have done it with out the Afourians....

Great news you have it running nicely again.

Food for thought - why was the carburetor gunked* up?

Perhaps there are issues upstream that, until resolved, will continue to gunk things up?

Peter

PS - I think the technical term is actually "KRUD" per Dave Neptune

Ha ha ha ha ha ha..:D:D:D:D

Yup, Krud it was. Probably going to slip a fuel filter in the line. The mechanical fuel pump cup was gross, and I probably should buy a replacement. Since it is a copper line from the pump to carb, was thinking of putting it in front of the pump. Something to put on the list.

Bright work has now come to the top of the list as well as reverse adjustment.

Thanks again guys.

There's no downside to filtration but under the circumstances you describe you'll catch the krud before it reaches the carb while doing nothing to address the source of the krud. Make the filter easy to change and carry spares because I suspect you'll be replacing it often.

BTDT - I ended up taking the fuel tank home and found it full of rubber bits from a failing fill hose besides for random stuff from many years of use.
It got a thorough cleaning before going back on the boat and the fuel fill hose was replaced too.