A4 Overheating issues

[Fencer21]

The manifold exhaust on my A4 is melting the hose that connects to the wet-exhaust pipe (the one that runs out to the transom) causing the hose to rupture and spew water and exhaust fumes everywhere.

I can't figure out whats causing this overheating. Water is ejecting out of the transom so it appears the water pump is working, I can't seem to see anything that is out of the ordinary as far as the connection of the hoses go.

The temperature gauge is showing the engine is running at optimal tempertures so it seems the thermostat is working.

Could it be the exhaust manifold could be going bad? And is that replaceable?

This problem really has me baffled. Has anyone ever run into this sort of thing

 

[jkenan]

I am coming off of a major refit to my A4, as a result of many issues, overheating for one.

First things first: Is your hose engine rated? It should be the black, reinforced hose designed to withstand high temperatures.

If so, then you may have a scale build-up causing blockage inside your exhaust manifold. I had the same issue. Water was coming out my transom (although not at the same rate as when the blockage was cleared), but the engine was overheating with a temp reading of 240! Didn't melt anything (which is why I'm concerned your hose may not be proper engine hose). To clear it, I had to remove the steet-el fitting where water exits the manifold. First time, I found it completely blocked with scale that had come loose inside the engine. I picked it out/broke it up with needle nose pliers, and hooked up the hose again, and ran the engine. After repeating the process of picking it clean and running the engine again several times, I was able to get it completely cleared.

I still inspect it once in a while, and find some bits of scale, which I pick out. I have since converted to a fresh water cooling system, and hope this will reduce the scaling issue, but I don't overheat anymore.

Don Moyer at Moyer Marine (moyermarine.com) is an excellent resource for guidance on the A4. He will have any parts you may need for repair, and was a great help to me. My wife and I sailed our 'new' Ericson 29 down the Chesapeake from Rock Hall, MD, down the ICW, through the Pamlico, and into Oriental, NC. Had engine trouble the whole way (it hadn't been worked that hard in probably 15 years). Don was a huge help to me on that trip, helping me troubleshoot the issues and finding a resolution. After several upgrades, bloody knuckles, and lots of learning, I have not had any problems with it since, and it runs like a charm. At the very least, buy his A4 service and overhaul manual.

Good luck.

John

 

[Fencer21]

Thanks John, I'll take a look at that this coming weekend.

Yeah the connection hose is rated, and I did have a chat with Don Moyer on the phone last month and his primary concern was for me to insure the water was flowing through the engine before mixing with exhaust. In other words he says it shouldn't have gotten that hot that quick.

Thanks again John...

 

[rgoff]

I just ordered some new "wet exhaust" hose to replace my factory installed PVC pipe that connects the vertical exhaust riser (that mixes exhaust fumes and water) to the transom. It is rated for 200 degrees. I think the PVC says 185 degrees.

If your hose is 200 deg rated and the exhaust water "normal temp" (165 or so), then it would seem like it is melting because the exhaust heat is not sufficiently cooled in the riser. If you have much water flow at all, though, that seems unusual. The way my riser is made, the water "encircles" about 80 percent of the height of the inner most riser pipe that transfers the exhaust to the outlet.

Any way to measure the temperature of the water coming out the transom?

Good luck,

 

[valentor]

Several years ago, my A-4 was running very hot, but still pumping water.

At the suggestion of Don Moyer, I disassembled the tubing path from the water pump to the manifold where I found and removed several little bits of a previously destroyed impeller. I was also surprised to find that the thermostat was frozen in the open position - so I replaced that too.

The engine has been running at a very stable 165 degrees ever since.


-Steve

 

[Art Mullinax]

Vertical Exhaust Riser

Several years ago I had to replace the vertical exhaust riser on My E29. The top cap had started to rot away from years of hot exhaust and water. It made the lazerette smell like exhaust fumes but made the cockpit seat nice and warm during the winter sails! I removed it from the boat, cut it open to measure the pipe needed and started welding. The exhaust pipe inside the riser had started to rot (rust) out also. Had this not been caught early, cooling water would have started entering the exhaust manifold and cylinders.. This may not be the source of your problem but deserves checking.
Art M

 

[Emerald]

Another trick you might try is to force the water through the block and around the cylinders by pinching off the bypass. If you look at the side of the engine with the starter and water pump, you will see that a hose runs from the water pump to a "T" on the side of the block and from the "T" it then runs up to the thermostat. Take a pair of vice grips and pinch of the hose between the "T" and the thermostat, and you will force the water into the block and past the cylinders. See if your flow stays the same and if your temperature changes. If you get cooler, and flow may decrease, it would indicate that you've accumulated corrosion in the block. For moderate corrosion, you can do a soak and flush with a muriatic acid solution. You can find muriatic acid at the hardware store. Take a 5 gallon bucket, put in 3-4 gallons of water, and top off with up to a gallon of the acid - remember to add acid to the water, not the other way around! Disconnect the suction/intake side of the water pump (make sure you close off the thru-hull first!) and put it into your bucket. With the bypass pinched off, and the thermostat removed (but housing assembled), crank/run engine long enough to suck up the bucket. Shut down and let it sit for about 20-30 minutes. Reconnect water intake to thru-hull, and run engine to flush clean. Be careful of fumes from the acid collecting in low places (your cabin) and overwhelming you. Don't leave an open bucket with acid down below any longer than necessary to run it into the engine.


-David
Independence 31
Emerald