08-21-2012, 09:07 PM #1
- Join Date
- Aug 2012
Can You tell I need a crank shaft after a compression test?
I have a '98 1100stx. I have been chasing problems for about a month. I have built carbs, changed battery and fuel. replaced fuel filter, changed plugs, and voltage regulator.
After the battery and carb work, it ran great on a wet test for 30 minutes the started running poorly and would not produce more than 4000 rpm. Replaced bad regulator and plugs. Still no improvement. Checked compression and found one cylinder dead, no compression. Not wanting to deal with it , I took to dealer. Dealer wants $3500 to replace all pistons and rings plus crank shaft. The dealer has only run a compression check, which I told them that number 3 was dead, and they gave me this estimate.
I would appreciate some input on this. I do have enough mec skills that I could do this job, but no time. I was hoping rings and pistons only, why a crank too?
Your thoughts and expertise is greatly appreciated.
08-21-2012, 09:21 PM #2
Take it to someone else. There is no way they can tell you you need a new crank without some other checks first. Your ski is only worth as much as they want to charge you.
Best bet bring her home and get a service manual. Pull the jug (is it # 1 or # 3? PTO or Mag piston usually) Yes your crank could be out of phase but you can't tell that with out some other things first.
Many times you can fix an issue like this for 100.00 to 300.00 $. You got wrenches, guys here will walk you thru it.
08-21-2012, 09:25 PM #3
when a piston fails it sends metal upside and downside, likey that pieces have found there way to the crank and bearings or the crank has failed also if an oil line came off that caused the damage.
08-21-2012, 10:10 PM #4
- Join Date
- May 2008
- Elephant Butte New Mexico
$3500..wow..they must have some super secret nada guide to try to sell you a job like that.
Book on that ski is $1750..any fix better be inexpensive., but like 123456 says the crank is likely contaminated with flak and virtually impossible to clean.
That's a pricy bit for sure.
If you open it up and it's not looking like a disaster, you _might_ get by on the cheap, but it's going to take a little work on your part to pull it off.
08-22-2012, 12:29 AM #5
Crank POSSIBLY damaged but although there are ways to determine some things before torn down I did not read where any of this was communicated, at all.
1. Compression test shows bad cylinder.
2. Removed bad cylinder and assess damage.
3. Check crank/bottom end out.
A blown slug does not ALWAYs mean bottom end is shot. Check with Rock County Jetski for parts. There are others also. SBT sux but sometimes...
08-22-2012, 10:57 AM #6
If you would be using the ski for family recreastion, you should consider investing on a (used) 4-stroke ski before spending anymore time/effort on this one.
08-22-2012, 02:44 PM #7
08-22-2012, 05:12 PM #8
I think damage to the crank, while possible, is an uncommon event. Three of my 750s have lost pistons and were rebuilt without replacing the crank (one has a bad crank and I will install a replacement).
On the Yamaha Jet Boat site, we see seized pistons all the time because the oil lines fall off. Perhaps less than 10% result in crankshaft damage.
I'd tear it down and inspect it. Spin the crank by and and carefully listen/feel for any roughness. Any at all is bad. Remove the reeds and you can get a better look at the bottom rod bearings. They should be shiny. If not, it's bad.
If the bearings are shiny and smooth, I'd go back together with it.
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