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4 tec crank tunnel repairs

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Steven Mace

Steven Mace

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Hey guys.. 4 tec crank tunnel.. Anyone got one welded and repaired? looks like the engine i have has had a main bearing spin or some problem a while ago. thinking if anyone has had one welded and tunnel bored before? Anyone know the specs of what it should be mesuring? If it comes to it im just going to put bearing retaining compound on the bearing and stick it back in ;) (But would love to fix it properly)

Thanks

Steve
 
Hey guys, doing a bit of research into this. Looks like im not the only person who has had a spun main bearing in a 4 tec engine that has made a bit of mess with the case. So after a few phone calls to seadoo shops they said replace the cases. Called a few machine shops they said they might be able to weld, tunnel bore and repair the cases but how much am I willing to spend. So still thinking about options. They only need to skim a bit of metal from the cases and need bigger bearings to fit right..?
Well few people mentioned about using bmw bearings when you machine the crank down .5mm so got me thinking what size in the OD of the bearings? Is there some other engine out there that could be close?
Seadoo book has given us a crank measurement of 50.01mm max and 49.91mm min main journal size. So the search is on.

Found BMW bearings on “King bearings” they measure 49.97mm ID – 53.59mm OD and 17.6mm wide. If they are the ones they sell and that’s the bench mark I continued..
So “if” 53.59mm (I will have to measure this) is the main tunnel measurement and want to skim a bit what else is there..

Honda 49.97mm ID – 54mm OD – 19.96mm wide (Could trim these down) being 54mm OD would give .4mm material to remove. so BMW bearings are 17.6mm wide what else is close to that…
Mazda 49.93mm ID – 53.99mm OD – 17.5mm wide. (That’s close! And give .4mm to remove)

Ohh mercury marine use a bearing that’s 49.50mm ID (Would have to skim .5mm off crank and its 54.30mm OD (give you .7mm getting better)

There is lots of bearings :)

Well food for thought.. might have to go home and get the measuring stick out.
 
I think there's a decent chance of locating a bearing that will work fine. Not sure why a machine shop can't line bore the block for you and select the bearing. My concern would be maintaining the correct distance between the crank and camshaft so the timing chain fits correctly, they should be able to nail that too, IMO.
 
its only one main that needs the work, the rest are fine. but few more days and machine shops are opening back up for the new year and ill find out more and post it up. seems a waste of a block/case :)
 
I agree, not sure why a decent machine shop can't straighten that out for you. I guess they could bore that journal to fit a larger bearing then hone bore the bearing set to get everything lined up for the crank.

I think if I were you, I'd also get them to assemble the long block.

Should be better than a new factory setup if they know what they're doing, as long as it doesn't cost too much, I guess you'll find out once you take it to them. I've had good experience with having this type of work done in the past and I believe the results are better when they do the assembly work.
 
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Not sure if you can disassemble and check clearances on those 4-tec oil pumps or not but I usually spring for a new oil pump and don't even fool with the original mainly b/c the machine shop always insists on a new pump anyway.

I have reused oil pumps before, only after checking them over closely. Could be some junk may have gone through your pump, considering one bearing spun might have had low oil pressure issues?
 
oh shit yeah. low oil pressure for sure. the big end bearing was paper thin and under neath the piston has little bits of alloy bearings stuck to it.. all filters and screens full of metal. :( but ill bring it alive again. i want to here this SC whistle. im having a quiet day at work today so i have been bringing some parts into work and checking them out. Just wrapping my head around this carbon seal on the drive shaft.. Thats all that stops me sinking.. wow. :facepalm:

IMG_3669.JPG
IMG_3678.JPG

Im going to thow it on the axe stone and square it up. (brand new stone)

Measured tunnel quickly last night. if anyone needs the spec the good mains measured 54.06mm - 54.04mm .. the bearings are 21mm wide aswell.
 
Re surface the stainless collar replace the carbon ring and replace the bellows if the rubber feels hard. The rubber bellows applies the tension that keeps the carbon ring against the collar when the bellows get old and hard you lose tension which causes cavitation on hard starts.

I replace the bellows and carbon ring every two years as preventative maintenance if the carbon ring breaks you will sink faster than you can say oh ****.
 
Just checking my boot, its not rock hard but not soft like a cars steering boot or anything. i noticed in the shop manual there is measurements for boot lengths for all other models but nothing for 4 tec.. you near your spare and have a ruler in your back pocket?
 
Well I got the carbon ring and metal seal ring that runs on it out and ran them around some 240 grit wet and dry garnet paper. come up great. I put them together and blew on them and couldn't get any leaks.. Have a look at the picture..
carbon seal.jpg

I measured the boot. its 75mm (1mm shorter) and is 50mm Inside diameter. but 1mm shorter should be fine. :)

Thoughts guys :thumbsup:
 
Steven Mace said:
Well I got the carbon ring and metal seal ring that runs on it out and ran them around some 240 grit wet and dry garnet paper. come up great. I put them together and blew on them and couldn't get any leaks.. Have a look at the picture..
View attachment 29165

I measured the boot. its 75mm (1mm shorter) and is 50mm Inside diameter. but 1mm shorter should be fine. :)

Thoughts guys :thumbsup:
Click to expand...

No way I would reuse that carbon seal with wear like that. This is not a part to cheap out on. If you do use it at least install a bilge pump cause you might need it.
 
Yep, the inner diameter of the carbon seal will naturally ride on the drive shaft I think to keep it centered with the stainless ring and there's no avoiding this? Thus, eventually the egg-shape of the inner diameter will become more pronounced as wear occurs.

Also, as the carbon seal ID becomes larger so I can imagine it would be more prone to wobbling under the right conditions and if that began to occur could rapidly destroy the carbon piece.

I agree a bilge pump is always a good idea on any boat or ski. And if for instance the seal were to fail completely I guess the jet pump wouldn't work too well (A big clue something has failed as air is sucked from the bilge and into the impeller) so it might be a good idea to have a rag available to wrap around the seal/bellows to slow the gushing leak until the ski can be beached?

Maybe if you're far from shore and the seal fails the small ski bilge would fill too quickly before the ski could be moved to the bank and not much can be done to avoid flooding the bilge? Not sure how fast the bilge can fill but it's a function of how much water can be pumped by the bilge pump, how large the leak is, and the amount of time it takes to fill a small bilge.
 
LouDoo said:
Like us Yanks say, a boat is a hole in the water in which you pour money.

Lou
Click to expand...

Well feeling depressed. Seen a bunch of machinists and no one wants to touch my 4 tec block. They say it's screwed. Great now what.? Anyone got a spare block or short engine?
 
well ran into a local seadoo guru today that said maybe a bloke that he uses might be able to work his magic.. so Tuesday next week might be sending the block to get checked out. he said about machine the mains, making a sleave to sit the main bearing in..
 
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