Balance Shaft and Engine Problem: HELP
08-24-2015, 05:35 PM
#1
Intermediate
Thread Starter
Balance Shaft and Engine Problem: HELP
Guys, I am desperate for help. I bought an 1985 944 on eBay a couple weeks ago for my son and posted about the horrible sound coming from the motor. It was a birthday present that he was supposed to be able to drive to school this year. Well, school started today and the car is at the shop.
Lots of you responded to my previous post with thoughts and I was greatly appreciative. But, here's the deal: upon removal of the upper balance shaft cover, I found that the bearing is totally toast (in pieces), and I guess the shaft has been bouncing around in its slot for a while...boring out the slot to a degree that my mechanic says the block is unusable. Experts, please share with me what toy see and what my options are.
Lots of you responded to my previous post with thoughts and I was greatly appreciative. But, here's the deal: upon removal of the upper balance shaft cover, I found that the bearing is totally toast (in pieces), and I guess the shaft has been bouncing around in its slot for a while...boring out the slot to a degree that my mechanic says the block is unusable. Experts, please share with me what toy see and what my options are.
08-24-2015, 06:04 PM
#3
Rainman
Rennlist Member
Rennlist Member
Simplest solution- delete the balance shafts. If you've got a reason to pull the oil pan or cross member, fit a reinforced oil pump pickup and may as well do rod bearings.
With deleted shafts, keep an eye on oilpressure and inspect the fuel rail from time to time for cracks caused by vibration.
With deleted shafts, keep an eye on oilpressure and inspect the fuel rail from time to time for cracks caused by vibration.
08-24-2015, 06:15 PM
#5
The simple answer is your mechanic's diagnosis is correct. You could take the cover and engine to an experienced welder and he could lay stringer beads on the block and cover. You could then have then line bored. With that said Spencer's plan would be much cheaper and easier.
08-24-2015, 06:15 PM
#6
Rainman
Rennlist Member
Rennlist Member
The bearing is a replaceable part. I can't tell from your picture if the bearing was totally worn through though or if it's still there.
The engine will run just fine as a balance shaft delete, you will just notice more vibrations around 3000-6000 rpm. And as I warned above they have a tendency to crack fuel rail mounting points and oil pickup tubes, but if you reinforce and regularly inspect it should be OK.
User sausagehacker, also in Texas, has been running a balance shaft delete engine for some time now. Hopefully he can chime in.
The engine will run just fine as a balance shaft delete, you will just notice more vibrations around 3000-6000 rpm. And as I warned above they have a tendency to crack fuel rail mounting points and oil pickup tubes, but if you reinforce and regularly inspect it should be OK.
User sausagehacker, also in Texas, has been running a balance shaft delete engine for some time now. Hopefully he can chime in.
08-24-2015, 06:22 PM
#7
Intermediate
Thread Starter
What was supposed to be so much fun for my son has turned into such a mess. And yes, I will NEVER buy a car without seeing it and driving it again.
My mechanic is trying to find a new motor. What would this cost to replace and put in?
Also, 2 other fast questions: 1. If I go the delete route, do you plug up the oil opening in the upper shaft housing (and with what)? 2. Is there any need to remove the lower balance shaft if there is no belt on?
My mechanic is trying to find a new motor. What would this cost to replace and put in?
Also, 2 other fast questions: 1. If I go the delete route, do you plug up the oil opening in the upper shaft housing (and with what)? 2. Is there any need to remove the lower balance shaft if there is no belt on?
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08-24-2015, 06:31 PM
#9
Rennlist Member
Yep, can confirm it's fine. I have been daily driving it up until recently, but only because Houston traffic is bad enough without deleted AC. I strongly suspect the motor was rebalanced at the crank after the delete, since the crank was machined (lightened and knife edged). I did have to set the idle a little higher though - about 1100 rpm, because it would quake below that. My motor mounts are on the way out though. I can idle it at about 850 very smoothly now due to MegaSquirt's semi-sequential injection, but that's probably neither here nor there for you.
Spencer brings up an important point about reinforcing the oil tube pickup... don't skip that step! I honestly have no idea if mine is reinforced, I bought the car this way. I'm assuming it is because everything is solid so far.
The way mine were done looks pretty simple... the covers are left on, but plugs were simply welded in. I'll take pics if you are interested. I guess there are many ways to do it, you just need to consider the oiling passages.
If you aren't up for all that, you can probably find a known good used motor for under $1000 without even trying. Maybe even under $600 if you hunt.
Spencer brings up an important point about reinforcing the oil tube pickup... don't skip that step! I honestly have no idea if mine is reinforced, I bought the car this way. I'm assuming it is because everything is solid so far.
The way mine were done looks pretty simple... the covers are left on, but plugs were simply welded in. I'll take pics if you are interested. I guess there are many ways to do it, you just need to consider the oiling passages.
If you aren't up for all that, you can probably find a known good used motor for under $1000 without even trying. Maybe even under $600 if you hunt.
08-24-2015, 08:09 PM
#11
Rennlist Member
The easiest thing to do would be just to leave the balance shaft belt off, no? Then you don't have to worry about sealing up the empty housing and the shafts aren't spinning and wrecking things up further.
Running with no balance shafts may eventually cause fatigue damage but it won't cause the engine not to run in the meantime. I'd just delete them and not worry about replacing the whole motor at present.
Running with no balance shafts may eventually cause fatigue damage but it won't cause the engine not to run in the meantime. I'd just delete them and not worry about replacing the whole motor at present.
08-25-2015, 05:02 PM
#15
Intermediate
Thread Starter
Went the route of doing the balance shaft delete today. Plugged the oil pick up hole, put everything back together, and NO oil pressure at all. Ugh. What does this mean?