Overheating woes

[sousou]

Atomic 4 Cooling Issues

Hello Everyone! It’s been an absolute delight reading this forum as I’ve familiarized myself with the majesty of the A4!

Recently acquired an early Ericson with an Atomic 4 V-Drive. It cranks and runs like a champ, but will slowly overheat while under load. It’s raw water cooled, and since I’m in saltwater, I try not to let the temp creep up too high above 140. TSTAT is 140.

Acid Flush is near the top of my list, but there are a few things I wanted to understand before going down this route, as I’m concerned it might create more issues given the engine’s age.

I verified the thermostat was operating correctly, but when I removed the housing it looked a little corroded on the inside. From what I’ve read, a corroded housing unit may impact the effectiveness of my TSTAT. To isolate this as the culprit to my overheating problem, I warmed her up and clamped the bypass hose to send the water directly through the engine.

When I clamp the bypass hose:

• No noticeable decrease in engine temp after 5 minutes of clamp
• No noticeable difference in water flow out of exhaust before/after clamp
• Exhaust started producing white smoke/steam. I’ll record some video this Friday for confirmation.

I’ve scoured the forums and so far haven’t identified a similar case. I’d like to have a better idea of what’s causing the smoke/steam before I perform the acid flush.

Summary:

• Engine slowly overheats under load at mid-range throttle
• Good water flow at idle and under throttle (I’ll link videos for outside verification)
• Clamping bypass does not noticeably impact engine temp but does cause white smoke/steam.
• San Francisco Bay so water temp is cool and salty.
• Oil is ready for a change, but is not milky

[Dave Neptune]

Flush or flush

sousou, first welcome to the MMI Afourian Forum. You may not need an acid flush if you have not tried a vinegar one yet. Simply put just drain the block and disconnect the feed from the water pump. Now be sure you can attach a pieces of hose that will be long enough to raise higher than the engine. Now disconnect the hose at the manifold exit and again have a piece of hose to attach and be able to raise above the engine. Now simply fill with vinegar and let it sit for a day or three.
I suggest that you remove the t'stat when doing this and not reinstalling until the vinegar flush is done and you have run the engine for a bit to get anything loose out of the system before you reinstall the t'stat. You can also clean the t'stat with vinegar too. The t'stat can catch KRAP and foul the flow otherwise.
Note if you find a diminished flow after the flush start at the manifold exit and look under the fitting. The end of the manifold is a common place for that that has shook loose to accumulate. Just poke it with a wire to break it up so it will be able to pass through.
My ole Ericson's A-4 is now on it's 43rd year and is also a raw water engine here in SoCal.

Dave Neptune

[Mo]

As per what Dave said. I've never had the engine overheat and do an muriatic acid flush every 3rd season before launch whether I think I need it or not...it's just a maintenance thing for me.

I also run with no thermostat and have a by valve. Dave has a slightly different set up that may very well work even better. This spring I purchased an infra-red thermometer and here are my readings with the boat cruising at 5 to 6 kts for hours on end.
-head 98 to 102 degrees
-block 140 to 142

This year my fuel mileage has been the best ever at (I figure) in the .6 to .7 gallon range per hour...that's not bad for these engines. I do a couple of other things a little different as well that I'm sure helps with dependability.
-15w40 diesel oil change at 20-25 hr interval (almost 6 yrs doing that)
-NGK XR4 plugs...just finishing 3rd season on them...not an issue and never fouled...these are not the recommended ones as per manual but were recommended by a local A4 rebuilder. So far so good.

Take what you want from it but has worked great for me with no issues.

Good Luck and I hope you get the problem sorted out.

[sousou]

Thank you for the replies. Dave, Mo, I think I have both of your setups committed to memory!

Not sure how I managed to leave this out of my original post, but I completed a full vinegar flush several weeks ago. Some junk came out but not much and I continued to experience the gradual overheat under sustained load. This is what initially led me down the path of considering a stronger acid flush. However, I put that on hold when I started investigating the adjustable bypass.

I’m definitely considering running with no t'stat with an adjustable bypass, but when I tested this by clamping the hose, it caused the engine to produce the white smoke/steam I mentioned earlier.

I'm really interested in thoughts on what might be causing that smoke / steam when I clamp the bypass.

In terms of next steps:

• Any thoughts on whether to go ahead with flush (no stat) and then perform actions below? Or just start with the physical checking of the different systems?
• Check end of manifold for accumulation
• Work my way up though systems to look for more junk
• Take some photos and videos to share

[JOHN COOKSON]

You're overheating because there isn't enough flowing through the engine and out the exhaust.
The culprits are a blockage or a water pump problem in a RWC engine.
Attach a hose to the manifold outlet and aim it into the cockpit or bilge. Start the engine and rev it up a bit. You should see good healthy output - like a garden hose.
If you are still overheating after you get reasonable flow through the engine it's time to look at the exhaust system.
A few random thoughts:
Did you verify the thermostat's correct operation by heating it in a pan of water? I'm sort of thinking when you clamped the bypass it reduced the total water flow through the engine and what little water made it through the engine turned to steam in the hot exhaust system. In any case I'd leave the thermostat out until you get this sorted out.
Have you had a look at the water pump? Maybe a piece of impeller broke off and is causing a blockage at the T fitting at the side plate. Also blockage in the strainer before the water pump.

Best of luck.

TRUE GRIT

[Dave Neptune]

Hmm

sousou, if you already did a vinegar soak, I would first look under the manifold's exit fitting. Also follow what John says for flow issues and something may just be stuck under that fitting~quite common. You can do both at the same time. There may also be KRAP blocking the t'stat so I would pull it out FIRST, leave out for a bit while testing the engine and the t'stat.

Don't worry about seeing steam in the exhaust to much~remember hot gasses from the engine and the warm water are mixing so some steam should be expected. It is far more noticeable in varying atmospheric conditions than actually being an overheating indicator.

Dave Neptune

[robshepherd]

Impeller?

Adding to John's recommendation to check the impeller, I just wanted to mention that I had an impeller fail this summer because the key way separated from the body of the impeller. When I opened the cover on the pump it looked like everything was fine, and there were no broken blades. But when I went to remove the impeller, only the center of it came out!

Just a thought for you. -Regards, Rob

[yeahjohn]

I just switched over to the 202m7 water pump and the thing blows water out of the back of the boat, before I always just had a modest little burp of water every few seconds. If you are not seeing a lot of water coming out of the discharge I would think your pump may be suspect.

[sousou]

Appreciate all of the tips.

I pulled apart all the hoses and cleaned out some really nasty junk.

Running without the tstat the temp won't go above 100, so it seems like I've cleared out all of the blockage.

When I added the thermostat back the temp climbed up to 160 or so, albeit slower than previously.

Thermostat was working fine when I last tested it, so I think the culprit may be the tstat housing. Will check again tomorrow, but it almost seems easier to go the manual bypass route at this point!

I'll report back later this weekend!

All the best!

[sousou]

There was a thread I saw a few months ago that demoed the amount of water coming out of A4.

Here's my trusty A4 after cleaning the manifold. Note it was a wet 50 degrees when I recorded the video.

http://youtu.be/P1u5IL1ZGX0

[JOHN COOKSON]

Appreciate all of the tips.
Thermostat was working fine when I last tested it, so I think the culprit may be the tstat housing. Will check again tomorrow, but it almost seems easier to go the manual bypass route at this point!
All the best!

I didn't reread the thread. Have you tried clamping the bypass? If clamping brings the temp down then a valve would be a good idea.

TRUE GRIT

[sousou]

Yes -- and eventually I installed the bypass kit from Moyer. Everything is working like a dream...expect the fuel pump...see other thread

I just added this video as another reference point for water output in A4. I found the other videos extremely useful to determining whether i was getting sufficient flow.

My overheating problem could be marked as "Resolved." At least for now!