95 mercury 3 litre burning propshaft seal

**whoblegear** · 07-11-2016, 09:36 AM

My 95 3 litre is eating propshaft seals again, I went thru this last year, found out my tuner was clogged, and bad poppet. I fixed those issues and my problem went away. The reason why I am posting here is I suspect a bad propshaft support bearing to be the problem. Just wondering if anyone else has seen this problem before. It seems to be getting hot judging by the color of the bearing and propshaft, and the seals fail because it seems like it builds too much pressure and pushes them out. What do you guys think?

**mercace** · 07-11-2016, 04:12 PM

I believe the fix was to plug the drain holes on the gearcase with a 1/4" brass pipe plug and drill an 1/8" hole in the center of plug. The drain holes are located just in front of the gear case mounting studs closest to the transom.

**whoblegear** · 07-12-2016, 03:36 PM

Thank you, what exactly does that supposed to do?

**mercace** · 07-13-2016, 08:21 AM

The water drains out of the mid section to fast and can cause overheating and the carrier to overheat and burn the seals. By plugging the holes and restricting the flow it holds more water between the can and the liner.

**whoblegear** · 07-13-2016, 12:17 PM

Ok thank you, I will be doing that

**whoblegear** · 08-06-2016, 11:04 PM

Ok I replaced 2 bearings in the lower unit because I noticed some minor pitting, my mid section drain holes are 1/8th inch, took it out today an ran it wot for probably 5 minutes, hit a sand bar :/ and spun my hub. I limped it home. Took prop off and my efen outer seal is crispy again wtf! There was some grass wrapped around the shaft but I don't think that is what caused the burned seal. How important are the small dump holes in the exhaust plate? If one was clogged with a piece of sand would it cause the seal to burn? I know my filler block is burnt as well, exhaust must be getting too hot.

**whoblegear** · 08-07-2016, 11:57 AM

Bump

**dompie99** · 08-07-2016, 06:01 PM

I hve the same issue, my filler bl;ock is always burt after two nomths of riding

**XstreamVking** · 08-07-2016, 07:49 PM

I have an old 98 225 efi 3.0 that burnt the hub out of any prop I put on it. They have a smaller water pump tube and 2 smaller strainers in mid for the water to get to the lower housing. Pulled it apart and it had shells blocking the strainers almost completely. Might be your issue....Newer motors have a bigger tube with one strainer that is larger in them. Don't seem to have the hi exhaust temps as the old ones did.

**dompie99** · 08-07-2016, 08:27 PM

in other words, you<re telling us to change the mid section tube to the bigger one ( an easy mod ) I went through the shop manual for these strainers that you mentioned and did not find them. can you point out where they might be located.

**whoblegear** · 08-08-2016, 03:08 AM

Thanks guys, I believe that my problem is that the holes are plugged with sand. I have seen the strainers b4 and wanted to get them as my 95 does not have them. Mercury discontinued the strainer.... I have came up with a new idea. I run in alot of shallow water, picking up sand and plugging the holes is inevitable. I think I'm going to drill two 1/8 holes in the water pick up strait back thru to the exhaust so my carrier gets water regardless. Good idea or bad?

**XstreamVking** · 08-08-2016, 08:51 AM

Put the motor on a hose flusher. See how much water comes out of the gear case exhaust at the prop. I would not drill into the water cavity as an experiment. Dompie, the older 3.0's had a diff tuner and adapter plate set up. Even the t-stat dumps were smaller. They also put water into the mid...I'm saying the old adapter/tuner system is not great, and the newer one is better. Whole lot better. Parts breakdown on boats.net.....

**whoblegear** · 08-08-2016, 09:20 AM

I wouldn't be drilling into the tuner or water cavity, but into the very bottom hole of the water intake on the gearcase. I did hook up the flush hose, pulled the lower and looked up there with a light. Both holes in the exhaust plate that dump water into the tuner that are aimed at the bearing carrier were plugged. I was able to get a piece of wire up there and knock the sand out so it flows again. I know this will more than likely happen again because of the kind of water I'm running in so I want a back up if they unknowingly clog again

**Chaz** · 08-09-2016, 07:54 PM

The real early 3.0 engine adapter plate was prone to cracking from the jacket to the exhaust runner. And yes they plugged the two small holes up pretty easily .
I drilled the two holes out to 3/16 th's and epoxied a 1 1/2 stainless tube in each one . As well as added a second pair of holes up the hill that would shower the exhaust runners . The stand pipes really do the trick , makes no sense to feed from the bottom of the funnel / sediment bowl ...

As was said , water (or lack of it) coming out of the carrier area while on the hose is the tell tale ...

**whoblegear** · 08-15-2016, 09:24 PM

I had a very similar idea as far as putting the "risers" in there, but don't feel like pulling the powerhead this summer if I don't have to. I did drill 1/8 in. holes in thru the lower water intake holes straight back into the exhaust part of the gearcase. I have no noticeable performance problems with that and it gives me peace of mind knowing that my carrier will stay cool regardless if those holes plug up. I put it thru some sand on Saturday and ran it hard all day, Im not sure if the holes are plugged or not but I will pull the lower to look this week sometime. I do know that my seal isn't leaking tho