Thermostat winterizing question

[Mark S]

I followed Chapter 9 pretty closely today with my RWC late model engine. I put a 3/4 inch hose nipple through the bottom of a five gallon bucket and ran a hose from it to the intake of the water pump. I had a fresh water hose running in the bucket and controlled its flow with a ball valve. I ran the engine for about 25 minutes at various speeds with plenty of water out the exhaust. The engine temperature never reached its normal operating temperature of 150-170 degrees, instead hovering in the 130-140 degree area. I attributed that to the engine being on jack stands and not laboring. Later, it occurred to me that perhaps I have no thermostat.

I drained the water from the block and exhaust manifold and extracted the engine oil. I put in MMO, 2 quarts to be on the safe side. I tried to remove the thermostat housing with a 3/8 drive and socket but the nuts and studs are frozen tight. I tried a penetrating oil which did no good. I didn't go any further so as not to break the studs. And if the thermostat were still open and the by-pass pinched I wouldn't need to take it out. I put a couple of gallons of antifreeze in my bucket and pinched the by-pass hose with a vice grip, tight enough to prevent flow, but not so tight as to damage the hose. I don't think much if anything could have gotten through.

By this time, the engine had cooled. I figured if the thermostat were closed and the by-pass pinched, no antifreeze would come out the exhaust. I started the engine and almost immediately I could hear the sound of coolant falling on the pavement. My wife, stationed at the stern, said plenty was coming out, as much as before. When I asked her the color, she told me "pink". I ran it long enough to have three gallons of antifreeze sucked in and then shut it off.

This has been a long preamble to my question: Am I correct in thinking that a closed thermostat and a pinched by-pass line would result in no coolant coming out the exhaust? If so, then I know the block is full of antifreeze. If not, then I don't know.

Thanks.

Mark

[rigspelt]

On stuck bolts and nuts...

I tried to remove the thermostat housing with a 3/8 drive and socket but the nuts and studs are frozen tight. I tried a penetrating oil which did no good. I didn't go any further so as not to break the studs.

I've learned only a little bit about stuck bolts refitting this new-to-me old A4, but had some successes. Get really good penetrating oil. (Warning, everything I've read says don't get that stuff on synthetics like engine seals). Examples of effective penetraing oils seem to be PB Blaster or Kroil. I've been using Kroil. Using a sharp pick, eye protection and a puff of air from an air can from the computer store, clean paint and debris from the joint between the bolt and whatever it is screwed into. Apply a little penetrating oil and let it sit a day or two. Tap the bolt gently in a manner unlikely to spread the bolt, break it or seat it deeper. Apply a well-ftting wrench and apply gentle pressue. Tap the wrench gently with little taps. If it won't budge, apply more penetrating oil and wait another day. I've had bolts let go nicely after 3-4 days.

Apply lots of patience. Understand how bolts hold into metal and get bound up. Sneak up on stuck bolts, don't muscle them. Try the phrase "speak to me". Think about the problem while sipplng coffee from an MMI Atomic 4 mug. It's worth prowling the Internet with Google for lots of accounts and ideas about frozen bolts. I see lots of good stuff about heat, but I haven't been successful applying heat, and it scares me around engines in boats, being an amateur.

[rigspelt]

Am I correct in thinking that a closed thermostat and a pinched by-pass line would result in no coolant coming out the exhaust? If so, then I know the block is full of antifreeze. If not, then I don't know.

I need to figure this out too. Here goes - let's see if I get this right (?):

A - cooling water hose from pump to T on side plate.
B - bypass hose from T on side plate to thermostat housing.
C - coolant passages in the block.
D - hose from thermostat housing to manifold.
E - coolant hose from manifold to exhaust.

SWC, engine cold: cold seawater flows from A to B and not into the block (C) at the side plate T fitting, because the thermostat is closed. From B it flows to D and E to exhaust at the transom.

SWC, engine warm: cold seawater flows from A to B, but because the thermostat is opening, some seawater diverts into the engine block at the side plate T, then through the block (C) to the thermostat housing, joining bypassed water from B in the thermostat housing to exit through D to E. Less seawater flows directly via B to D and E, because some is diverted into C. But all the warm seawater exits via D to E, whether it goes through the block (C) or bypasses via B. As the engine warms, the thermostat opens more and more, inviting more water to flow through C.

FWC: Cold seawater flows from the intake seacock via pump #1 to the heat exchanger, and warm seawater flows from the heat exchanger directly to the exhaust (5/8" hose, not 1/2", I just realized). Cool antifreeze/freshwater coolant flows from the heat exchanger to A, as above, except that hose E routes from the manifold to the heat exchanger via pump #2 (1/2" hose, as usual).

[rheaton]

I would expect you should see the antifreeze come out of your exaust. It is being pumped in through your engine, and will need to exit somewhere. Your bypassing the thermostat will control where, within the engine, it goes. I think your steps were correct.
Take care, Russ

[Don Moyer]

Your understanding of the bypass type of system used in late model engines is essentially correct - both in the case of SWC and FWC engines.

In actual practice, thermostats don't ever seem to completely block off the flow of coolant through the block and head. In the case of OEM thermostats, they simply don't close that tightly, and in the case of our MMI aftermarket thermostat kits (which do close more tightly), the thermostats have a small bleed hole in the movable valve assembly.

In the case of FWC engines, this leakage through even normally functioning thermostats sometimes makes it necessary to artificially close off the bypass hose completely during hot times of the year and at high power settings to provide maximum cooling. For this reason, we have gone to installing small ball valves in the bypass loops on all our exchange engines. You can see these valves in the new 360 view of an exchange engine by clicking "here" next to the "new star" on our home page. If you rotate the engine one click to the right, you can see the whole bypass loop configuration.

Don

[sastanley]

should we all do this?

Don,

In practice, when would you adjust the valve? Do you wait for the engine temp to go up and then close it perhaps 50% to see if it helps bring the temp down? I've noticed a pretty large range of operating temp from 140 to as high as 190 degrees when my raw water cooled motor is running under load. At idle, it tends to hover around 160.

Secondly, do you recommend this modification to other A4 users? I plan to replace all of the engine's hoses this winter, and this would be a great improvement to the "squeeze the bypass loop with a needle-nose vice grip" during the winterization process, (which is on schedule for tomorrow) as the boat gets hauled Wed AM.

Incidentally, does anyone know the sizes of the intake hose system (5/8" ID)? I need to put a piece on the intake side of the water pump to suck in some antifreeze tomorrow..I am not brave enough to remove the hose from the 30 year old thru-hull fitting with the boat in the water.

Thanks,
Shawn

[Don Moyer]

Shawn,

Start by closing the valve approximately halfway. This should be a good setting for most of the season. In the heat of the summer, or at anytime that you see the temperature climbing above 190 degrees, close the valve a bit more. There's nothing wrong with ending up with the valve practically closed.

We do recommend installation of a restriction in the bypass loop on all engines. As a frame of reference, Universal came out with a technical note in the mid 1970's which recommended placing a restriction in the bypass loop by filling the hose barb fitting on the inlet of the thermostat housing with lead and then drilling an 1/8" hole in the lead. We believe this procedure is a bit too restrictive and gives one no flexibility to adjust the restriction in cases where little or none is needed.

Don

[Mark S]

Thanks, Don, and thanks to everyone else, too.

I'm guessing from the amount of antifreeze that came out the exhaust that the thermostat was either open or not present at all. If the thermostat were closed and the by-pass pinched and antifreeze made it out the exhaust, I'm assuming that the volume exiting would be somewhat less than if the thermostat were open or not present.

Either way, my having pinched the by-pass means that antifreeze got into the block and antifreeze exiting the exhaust means it traveled the length of the cooling system in the block and must be present in the interior.

Mark

[sastanley]

Sounds good to me Mark..I will be performing this procedure tomorrow, if time permits...we are motoring the boat down to the travel lift slip, and then plan to change the oil (added one quart of MMO last week) and suck in some antifreeze.

I bought short piece of a 1/2" ID hose today..I hope that is right..the 5/8" looked too big.

[Mark S]

Sastanley,

All my hosing from the seacock to the strainer and from there to the water pump is 3/4 inch but I think I remember Chapter 9 (I left the book on the boat) talking about 1/2 inch hose. Chapter 9 is summarized in the General Maintenance category on this site. Anyway, good luck with it. I found it important not to ask the water pump to suck the water uphill out of the bucket; hence, my bucket with the hose coming out the bottom perched on the icebox and giving the pump a straight downhill feed.

Mark

[sastanley]

Thanks Mark, my MMI manual is on the boat too!!

I seem to recall from some other readings around here 1/2"ID was correct so that is what I got...I also got flimsy braided clear water hose, so it will stretch.

Thanks for the tip on the bucket..I am limited in my time tomorrow, so if I can't get things to go as planned, I'll have to come back and winterize when on the hard. I thought it would be easier to winterize in the water, but maybe not...I'll at least get the oil changed tomorrow when it is hot from the trip to the marina....much easier to pump out of the oil pan that way!

If i can figure out a way I may try another tip in here which was to get a nipple on the screw cap and then flip the bottle over..but it is getting late and I am not feeling very adventurous at this hour.

[Don Moyer]

Mark,

Just a short heads-up: Each year or two we get a report from someone who elevated their water supply above the engine as you seem to be doing and ended up flooding water back into their engine. Whenever you elevate the water supply above the engine, you set up the potential for the water to siphon out of the bucket after the engine is shut down and filling the exhaust system until the water backs into the engine. The solution if you want to continue elevating your supply bucket is to be sure to remove the hose from the bucket immediately when you shut off the engine.

Don

[Mark S]

Don,

That's good to know. Fortunately, I ran the engine each time until the bucket and the hose were empty and I could hear the pump growling in the bucket.

Mark

[sastanley]

When I winterized the boat on Tuesday, I used a funnel with about 3' of hose attached to the inlet of the water pump. Filled it, and had my safety officer (wife) hold it while I started the motor..and then poured it in as fast as it would take it. It probably took about 45 seconds for it to suck 6 quarts of antifreeze into the motor..once i saw pink coming out the exhaust, I shut her down.

This worked pretty well, except I could not get the 1/2" hose to fit over my corroded hose barb on the pump inlet..I was able to jury rig something though with a piece of larger hose and get it accomplished.

I see the bypass valve kit in the cooling section..I think I'll add it to my list of winter goodies from MMI!

[knitchie]

Winterizing

Just to share practices, I have a t-valve on the input side of the water pump that I put in a bucket of pink. I also remove the thermostat before winterizing, but don't pinch off the bypass. I catch the pink at the transom exhaust in another bucket and toss it in the bilge for good measure. I don't completely flush the pink out of the engine until spring. So far, it appears that the pink flows throughout the engine. Just need to remember to reinstall the thermostat in the spring.