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Atomic 4 temperature sending line too close to exhaust?

LPBlues

Member I
Hi all,
I've just purchased an E29 from '71. It's got an Atomic 4 rebuilt in the late 90's that has a heat exchanger for fresh water cooling. The engine just went through an inspection and passed with flying colours. We took it our for our first trip today to move it to our marina but had to turn back after about 20 min. because the engine appeared to be overheating. Temp climbed steadily to over 200 then 220. We would have shut it off as it went over 180 but we were about to enter a narrows and needed to stay off the rocks :). We eventually got the sails out and had a good sail back and just fired up the engine for a few minutes to get back into the slip. Engine still sounded good. Raw water seemed to be moving fine, strainer was full and active looking, water coming out the back of the boat as expected. The fresh water exchanger (radiator) was full, and I later checked out the impeller and that looked healthy. The former owner thought it could be the temperature sending line being too close to the exhaust (something that came up during the survey). The line is insulated from the front of the engine but becomes bare as it passes through the bulkhead over the wrapped exhaust pipe.

My question is: Should I insulate the line in this section (what with) and possibly suspend it from the top of the opening to keep it off the exhaust? Also, any other thoughts on heat issue?

tempsendline.jpg
 

adam

Member III
The pressure showed around 30 if I remember correctly.

30 is a bit low, but not terribly so. Next time you take the boat out watch the oil pressure a bit more closely and see if it drop low or acts eratically.

As for the wire, you could try just temporarily using a rag to temporarily separate it from the exhaust and see if that makes a difference.

You might also want to try tightening up the "oil pressure adjustment valve" on the side of the engine. I believe the pressure should be 40 with a warmed up engine.

And finally, not to disparage this amazing forum at all, but Moyer Marine has a forum which focuses on nothing but the Atomic 4 engine. If no one has an answer here, you should try there.
 

LPBlues

Member I
thanks!

30 is a bit low, but not terribly so. Next time you take the boat out watch the oil pressure a bit more closely and see if it drop low or acts eratically.

As for the wire, you could try just temporarily using a rag to temporarily separate it from the exhaust and see if that makes a difference.

You might also want to try tightening up the "oil pressure adjustment valve" on the side of the engine. I believe the pressure should be 40 with a warmed up engine.

And finally, not to disparage this amazing forum at all, but Moyer Marine has a forum which focuses on nothing but the Atomic 4 engine. If no one has an answer here, you should try there.

Thanks Adam, it will be a week before i can get back to her. I'll keep you all apprised.
 

Bill Sanborn

Member III
A4 Temp

Sound like a thermostat problem or something blocking the cooling liquid in the engine. What are you using for coolant, anti-freeze? What's the level? Any coolant in the bilge?
 

LPBlues

Member I
looks like anti-freeze

Sound like a thermostat problem or something blocking the cooling liquid in the engine. What are you using for coolant, anti-freeze? What's the level? Any coolant in the bilge?

Hi Bill,
it looks like anti-freeze to me. There is some in the bilge, and the leak seems to be near the impeller. I was hoping it was jut the impeller cover but without a mirror I can't see underneath to see if it's coming from somewhere else. I've tightened the cover after inspecting the impeller but haven't had a chance to run the engine again. The level is generally good, as in I top it up before running motor but after shutting it off the engine slowly drains over a couple of hours.

If the coolant isn't flowing, and assuming that the impeller is doing it's job, how can I test that? I'm assuming you're saying there could be a blockage somewhere? Is it as simple as taking off a coolant hose and connecting it to a hose and running water through the system?
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
We have had periodic unpredictable overheating due to air bubbles being trapped in the coolant, dislodging and then blocking coolant flow. This is most likely after any work has been done on the cooling system which could have introduced air bubbles.

However, one time this happened on the last day of a two week cruise after the engine had been running fine at normal temp the whole trip--go figure! But I had done some work on the cooling system the previous month, and it took that long for the air bubbles to work their way into a blockage. And then, even when I thought I had bled all the air out through the small valve, I checked it again the next day and sure enough, there was still some bubbling of air bubbles escaping--so small it's hard to see them, but they are nasty fellows when they cause an overheat!

I think that's one of the most likely causes of overheating, though as others have suggested, there are other possibilities to eliminate as well, but this one doesn't require any new parts, or expensive mechanics!

Good luck!
Frank
 
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LPBlues

Member I
I had done some work on the cooling system the previous month, and it took that long for the air bubbles to work their way into a blockage. And then, even when I thought I had bled all the air out through the small valve, I checked it again the next day and sure enough, there was still some bubbling of air bubbles escaping--so small it's hard to see them, but they are nasty fellows when they cause an overheat!

Good luck!
Frank

Thanks Frank,
how were you bleeding the air? is there a valve somewhere near the common trap points or is that a custom addition to your engine?
 

Bill Sanborn

Member III
A4 Temp

Quick and dirty thermostat test.

The hose from the cooling pump splits at T in the side of the block allowing cooling to either go thru the engine or bypass it thru the thermostat housing and then
to the manifold

When the engine is cold the thermostat is closed causing the coolant to bypass the engine and go to the exhaust manifold.

As the engine warms up the thermostat opens and allows some of the coolant to flow thru the engine and some to thru the bypass hose thus regulating the temp.

If the engine gets hot enough the the thermostat is supposed to close and force all of the coolant thru the engine and none thru the bypass hose.

Remove the thermostat and pinch off the bypass hose between the T and the thermostat housing which forces all of the coolant thru the engine all
of the time. The engine should run ok but never come up to temp.

Back in the old days when thermostats and their housings were very pricey I removed the thermostat completely and installed a ball valve in the bypass hose.
By opening and closing the valve the temp was regulated. Sort of a PIA but it worked once you found the sweet spot.

I have installed FW cooling since then and tied the ball valve shut but left it installed. In an emergency I could easily revert to SW cooling and still regulate temp.

Let us know what you find.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
I think it's standard on universal engines, but I don't know about others. However, I re-arranged the hose at the thermostat so I had to add another bleeder valve at the new high spot, and it wasn't difficult -- cheap to buy at an auto parts store and tap a new thread into the pipe.
Frank
 

LPBlues

Member I
Thanks everyone

You've given me a lot to look into. My confidence level is going up as I slowly remember my Power Mechanics class from the 11th grade :). Because my boat is currently moored over an hour's drive away I won't get a chance to look at it until Saturday. I'll let you know if I'm able to find anything. From looking at the Moyer site and with your help it feels like a coolant flush might be in order along with air bleed and thermostat function check.

One more question though, when I inspected the impeller (the potential site of my slow coolant leak) I noticed the cover plate gasket was not glued in, is that normal in the coolant system?
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
You've given me a lot to look into. My confidence level is going up as I slowly remember my Power Mechanics class from the 11th grade :). Because my boat is currently moored over an hour's drive away I won't get a chance to look at it until Saturday. I'll let you know if I'm able to find anything. From looking at the Moyer site and with your help it feels like a coolant flush might be in order along with air bleed and thermostat function check.

One more question though, when I inspected the impeller (the potential site of my slow coolant leak) I noticed the cover plate gasket was not glued in, is that normal in the coolant system?

Our original Oberdorfer pump used a paper gasket that usually stuck to one face upon removal... or sometimes both faces... and tore in pieces. :rolleyes:

IIRC the newer series one that I have now uses an O ring to seal the interface with the cover.

http://www.oberdorferpumps.com/pumps/rubber-impeller-pumps/n202m/

This one looks familiar.

Best,
Loren
 

LPBlues

Member I
interesting

Our original Oberdorfer pump used a paper gasket that usually stuck to one face upon removal... or sometimes both faces... and tore in pieces. :rolleyes:

IIRC the newer series one that I have now uses an O ring to seal the interface with the cover.

http://www.oberdorferpumps.com/pumps/rubber-impeller-pumps/n202m/

This one looks familiar.

Best,
Loren

The one on my engine follows the lines of the square/diamond cover with the screws going through it, it's a paper one. It moved freely once the screws were loosened.
 

LPBlues

Member I
any thoughts on that sending line? too close, wrap it?

Hi all,
I'm heading up to the boat today to investigate your helpful suggestions but I don't think I heard from anybody about my original question which was: Is that temp send line (in the pic) too close to the exhaust and should it be wrapped, and if so with what? Just wondering if anyone had thoughts on that specific issue.
 

toddster

Curator of Broken Parts
Blogs Author
Well, I wouldn't route anything through the same hole as the exhaust.

I'm slowly cleaning that area up myself. Did the house wiring last year. Engine wiring on schedule this spring. The PO just left sort of a tangle in there where it's hard to reach. And other problems.
 

Bill Sanborn

Member III
A4 Heating

I think that wire is a "red herring". The temp of the wire doesn't affect its ability to conduct electricity. If it was shorting on something you would probably see rapid, erratic movements on the temp gauge.

This wire on my E29 A4 is routed thru a bundle of other wires going to the inst panel. I am curious as to why somebody changed it. Indication the PO had problems?

It sounds like you want to move to new moorage. I think I would remove the thermostat and if the engine temp stays cool/low I would go ahead and move the boat.

In general it is not a good idea to have insulated wires laying about, I would replace the wire rather than fix.
 

LPBlues

Member I
wire or "line"?

I think you're right Bill, the wire is a red herring. But I'm not sure if this 'wire' carries current of any kind. It comes straight out of the front of the engine heat sensor. It doesn't look electrical to me.

I didn't get enough time with the engine today but it did overheat while running in idle at the dock fairly quickly even with the temp sending line off of the exhaust.

Also, I think I found my drip coming from the shaft of the fresh water impeller? see pic below. I couldn't get it orient properly but you can see the drop of coolant hanging from the underside of the impeller shaft housing area. Any thoughts on this?


 

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LPBlues

Member I
another update

I took out the thermostat today to see if it was gunked up but it looked pretty clean, at least compared to some pictures I've seen online. It's the brass, three spring "holley" kind I think. I've got it soaking in vinegar just to clean it up anyway but I'm guessing this is not it either, though I'll do a stovetop test with it to ensure it's functioning at the right temperatures once its clean. I'm thinking about an acid flush as there was quite a bit of slimy build up in the bottom of the thermostat housing.

Since the coolant leak appears to be located at the shaft of the oberdorfer pump I'll have to check it for play, maybe the seal is gone or the shaft is worn. I tightened the grease cup but maybe need to also rotate the shaft to spread it around. Not sure if that is supposed to just lubricate or also help seal?

At least I'm learning lots about this engine :).
 

Afrakes

Sustaining Member
Hot A4

LP: Have you opened the engine manifold and block drains to see if coolant flows from them? Pull the hoses and make sure that you don't have a piece of impeller vane stuck in one of them. When I rehabbed my 73'A4 I found both of those problems. Al Frakes, Port Kent, NY
 
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