Logo

Electrolysis damage...cause of overheating?

I'm going to try welding them before I give up on them

will depend on how deep the electrolysis has degraded the surrounding area.

grinding back an inch or two to clean aluminum is an easy weld job if the metal is solid


So is that an absolute that the little missing chip is likely to cause overheating?
 
I'm much more confident in my machining abilities to get the surface flat than I am in my mechanical abilities to properly swap cases and get the shimming correct.

that said, what $ would you want for your case and what condition is it in?

id love to find a good lower complete with the correct 1.47 gears for a reasonable price.

what are your thoughts on the aftermarket SEI lowers.

im disinclined to go aftermarket but may consider
 
Last edited:
Have installed numerous ones and all have had good results for both the 106 and 116 drives
If all things were equal, you could disassemble your unit taking out thew shim pack and measuring them and comparing them to what comes out of the case I have. If they mic the same I`d say just reassemble with the shim pack you removed .
 
Last edited:
id love to find a good lower complete with the correct 1.47 gears for a reasonable price.

Ayuh,... The gear ratios are determined by the Upper gears, not the lower unit,...
 
I'd suggest you disassemble the case if you are going to attempt the welding job.....the seals likely won't survive the process.....
 
Yes I've thought about how to preserve the seals. I'm going to TIG weld it with the case in a tub of water and wet towels around what's not submerged. I've had good luck localizing the heat with this method.

its definitely a concern though.

I havent looked at it at it too closely yet but I would think you can replace the seals without disassembling it. Am I wrong?
 
Ayuh,... The gear ratios are determined by the Upper gears, not the lower unit,...

thank you I hadn't checked part numbers to confirm that yet. Is this true for all alpha one gen 2 lowers? By your statement, is it safe to assume that all standard rotation alpha one gen 2 lowers are interchangeable?
 
thank you I hadn't checked part numbers to confirm that yet. Is this true for all alpha one gen 2 lowers? By your statement, is it safe to assume that all standard rotation alpha one gen 2 lowers are interchangeable?

In most cases.................some lowers have ratio also, such as 2:1
 
I have yet to see a repair to the water dam in a lower not cause damage to the engine. I have seen welded, JBWelded, fiberglassed, sheet Metal and Life Caulk.

Everyone (the fiberglass one waffled a cylinder on a Verado) damaged the engine.

Purchase an SEI lower if money is an issue. It is a lot cheaper than a Block.
 
Why not clean everything well and use JB Weld, then sand and file to flatness................

that picture was from when I had the drives serviced in July. As a temporary measure I discussed with and had my mechanic reassemble with silicon sealer filling in the damaged area.

this time I intend to do it properly with no more half measures.

The current theory espoused by my mechanic is that my overheating condition is being caused by the silicon repair failing. If he is correct then I wouldn't trust JB weld to hold up much better.

the overheating situation came on suddenly which indicates something chsnged quickly. At first I thought that my 16 year old manifolds and elbows were finally failing. So far I have removed the port manifold and elbow and they look to be in excellent condition. I did discover that half of my flapper valve is missing from the port side of the Y pipe. My mechanic does not believe that the missing half of the flapper would cause my overheating. His point was that if the flapper was restricting enough to cause overheating, I would also be loosing power...which I am not. Apart from the overheating the engine is running very strong. He believes the temporary silicone fix to the outdrive let go and is allowing exhaust gas into the water intake.

my parts should arrive today. I'm replacing manifolds elbows mounting hardware, water circulating pump thermostats flapper valves and all hoses and tubes. If it still overheats my mechanic told me to splice in a piece of clear tubing into the hose from the water inlet to the thermostat housing and look for bubbles
 
I have yet to see a repair to the water dam in a lower not cause damage to the engine. I have seen welded, JBWelded, fiberglassed, sheet Metal and Life Caulk.

Everyone (the fiberglass one waffled a cylinder on a Verado) damaged the engine.

Purchase an SEI lower if money is an issue. It is a lot cheaper than a Block.

I intend to repair properly. I'm not trying to save money by doing a shoddy repair but I also do not like to waste money replacing something that can easily be repaired. Why would welding not be a suitable fix? If the surrounding aluminum is sound it should be a simple fix and just as strong as when new.

if the surrounding material is not sound I'll replace the drive.

Where is the flaw in this approach?
 
The Lower unit is cast, and it's not aluminum. The crystalline structure of the cast metal (some alloy we have no idea what exactly. Clearly lots of zinc in there since that's what gets eaten away first in the electrolysis chemistry) does not take to welding very well. The repair will eventually fail from legions of tiny little gnomes with shovels and pickaxes beating away at it over time (or more technically a fatigue failure) which may or may not lead to a problem that is worse than the fix.
Thing is, you have it apart already so why not just get a good used lower and be done rather than reinstall a very questionable part?
 
I haven't made up my mind yet. I need to pull the drive first and have a good inspection first.

i do have an update though. This weekend i replaced the manifolds elbows exhaust tubes thermostat and all hoses. I also installed a remote oil filter kit while things were apart.

i noticed a few things... the old starboard elbow and manifold were in much worse shape than the port side. The center piece of elbow actually crumbled when I accidentally dropped it. There was blistering on he inside of the tube that connects the Y pipe to the 90 degree bend...looks like it was getting very hot.

the exhaust ports on the head had a little corrosion on the sealing surface. I scrapped and sanded back to clean shiney smooth metal but there were still a few small pock marks at the bottom of the two center exhaust ports.

The starboard exhaust flapper was desintegrated and gone.

i was able to reach into the Y on both sides and feel the connector. There were no pieces of the flapper remaining.

after reassembly the engine was noticeably quieter

the new starboard elbow got much hotter than the port side.

overall engine temp was perfect on the gauge. I ran it for 3 hours at normal cruise. 3100 RPMs for 90 minute round trip to lunch ��

I also ran it a bit harder for 5 minutes at 3600 RPMs with not increase in temperature.

I'm puzzled by the temp differential between port and starboard.
i only checked temps during first start up

I need to check again now that it's been run.

the steam that I was seeing after running is now completely gone
 
Typically, a blockage in the elbow--where the water and exhaust finally meet--will cause that side to run hotter (and the other side cooler).

Jeff
 
Entire system is band new oem mercruiser from the head to the Y just installed Sunday.

there is no blockage in the elbow manifold, etc.

could there be an air pocket? Do you need to bleed these on a new install?
 
Last edited:
The SB elbow running hotter is normal.

Push the throttle wide open and see how it does. That would be running it harder and the way it should be tested.. Besides if you cannot reach max RPM there is something wrong.
 
Next time out will push it to WOT
didn't want to open it up till I put it through a full heat cycle and re torqued everything.

the motor runs very well and has never protested WOT ...just ran hot doing it that one time which lead to this endeavor

I'm very pleased to hear you say it's normal for SB to run hotter....any idea why?
 
Last edited:
I know YOU didn't do this, but some people silicone the hell out of every gasket, and that alone can cause a blockage.

Jeff
 
From page 7B-5 of the Mercruiser service manual


1. Apply a 1/8 in. (3 mm) bead of LOCTITE 510 Sealant P/N 92-804874 around all holes
on both sides of a new fire ring gasket.
76360
a
a - 1/8 in. (3 mm) Bead of LOCTITE 510 Sealant
2. Assemble parts immediately and torque fasteners to specifications.
3. Allow sealant to cure 2-3 hours before starting the engine.

I was actually surprised by how much sealant Mercury says to use. I bought the exact Sealant and applied per the manual.

the only difference I can see between the port and starboard side is this one water tube from the intake manifold to the exhaust manifold (red arrow)
this is not my motor just a pic I found on line of one like mine.

13355588315_6970d9efc7.jpg
 
Back
Top