Engine rebuild woes - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 02-02-2013, 05:12 AM   #1
Elite Member
Thread Starter
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default Engine rebuild woes

My rebuild is not going as planned. Everything going smooth until the last rod cap. As soon as its torqued on the engine takes a great deal of force to turn. Loosening the studs allows the crank to turn freely. Loosened 1 2 and 3 rod caps and torqued 4 down and its at the same nearly impossible to turn crank. Caps installed correctly, standard size bearings, piston installed the correct way. Only thing we did to the crank was take some emery cloth and went around it a few times. Even swapped bearings with #1 and still same result. Also put in old bearings for ***** and giggles, no beans. I think its something stupid that might be going on. Any ideas would be much appreciated. Getting plasti gauge tomorrow.
SKMetalworks is offline   Reply With Quote
Old 02-02-2013, 08:57 AM   #2
Elite Member
iTrader: (12)
 
Join Date: Aug 2006
Location: Central-ish VA
Posts: 4,449
Total Cats: 16
Default

So you are saying even with the old bearings it doesn't spin? Or just with the new ones? Could be new ones are mislabeled oversize bearings. I guess you don't have an inside mic you can use to measure with do you? Also, are you 110% sure you haven't mixed up the rod caps at all?
neogenesis2004 is offline   Reply With Quote
Old 02-02-2013, 09:08 AM   #3
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,107
Total Cats: 518
Default

This happened to mine once, turned out I threw one old bearing in with the new. All the old ones looked ok, all 32 new and old bearings were "STD" size. One out of 8 with the rods is apparently enough to lock it up pretty good.
curly is offline   Reply With Quote
Old 02-02-2013, 12:44 PM   #4
Senior Member
iTrader: (1)
 
BogusSVO's Avatar
 
Join Date: Mar 2012
Location: Pensacola Fla.
Posts: 590
Total Cats: 191
Default

Are they the used factory rods? or new aftermarket ones?

I have come across 1 or 2 aftermarket rods that were a tad small on the big end bore.
BogusSVO is offline   Reply With Quote
Old 02-02-2013, 01:32 PM   #5
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,366
Total Cats: 1,327
Default

Quote:
Originally Posted by SKMetalworks View Post
Getting plasti gauge tomorrow.
You didn't take any measurements or use any plastigauge at all during the build?
Savington is offline   Reply With Quote
Old 02-02-2013, 01:46 PM   #6
Senior Member
iTrader: (1)
 
BogusSVO's Avatar
 
Join Date: Mar 2012
Location: Pensacola Fla.
Posts: 590
Total Cats: 191
Default

Quote:
Originally Posted by Savington View Post
You didn't take any measurements or use any plastigauge at all during the build?
Sav.... Not all guys are number junkies like us.

I would bet you have stacks of notebooks filled with specs from different builds from over the years.
BogusSVO is offline   Reply With Quote
Old 02-02-2013, 01:51 PM   #7
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Plastigage.

(Or however it's spelled.)
Joe Perez is offline   Reply With Quote
Old 02-02-2013, 02:08 PM   #8
Junior Member
 
Join Date: Feb 2012
Location: near Ottawa Ontario Canada
Posts: 49
Total Cats: 13
Default

3 things to check:
- Rod is not pushed to one side of the piston (too far forward or back along the length of the piston pin) so that it no longer lines up square to the Crank rod journal.
- piston is not turned in the bore (causing the rod to not be square to the crank)
- Piston is stuck in the bore (damaged piston ring, not enough end gap on one or more rings, piston has a nick during installation, ...)

Disconnect the rod at the crank and see if you can push the piston up the bore... All 4 pistons should have about the same resistance.
99Racer is offline   Reply With Quote
Old 02-02-2013, 03:01 PM   #9
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,366
Total Cats: 1,327
Default

Quote:
Originally Posted by 99Racer View Post
3 things to check:
- Rod is not pushed to one side of the piston (too far forward or back along the length of the piston pin) so that it no longer lines up square to the Crank rod journal.
- piston is not turned in the bore (causing the rod to not be square to the crank)
- Piston is stuck in the bore (damaged piston ring, not enough end gap on one or more rings, piston has a nick during installation, ...)

Disconnect the rod at the crank and see if you can push the piston up the bore... All 4 pistons should have about the same resistance.
1 and 2 are not reasonable causes of any problem, because they do not happen. Tightening the big end of the rod will ALWAYS line the piston up in the bore and line the rod up on the crank.
Savington is offline   Reply With Quote
Old 02-02-2013, 06:03 PM   #10
Elite Member
Thread Starter
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default

Plastigauge results as follows.
Cyl 4 .0015
Cyl 3 .002
Cyl 2 .002
Cyl 1 taper .003-.0015
SKMetalworks is offline   Reply With Quote
Old 02-02-2013, 06:10 PM   #11
Elite Member
Thread Starter
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default

Quote:
Originally Posted by neogenesis2004 View Post
So you are saying even with the old bearings it doesn't spin? Or just with the new ones? Could be new ones are mislabeled oversize bearings. I guess you don't have an inside mic you can use to measure with do you? Also, are you 110% sure you haven't mixed up the rod caps at all?
I replaced the 4th Cyl bearings with used bearings to see if it would turn after it was torqued and it wouldn't (however I couldn't verify this was Cyl 4 bearings). I micd the new and old bearings. Same width. Rod caps 115% mated with correct pistons.
SKMetalworks is offline   Reply With Quote
Old 02-02-2013, 06:24 PM   #12
Senior Member
iTrader: (1)
 
BogusSVO's Avatar
 
Join Date: Mar 2012
Location: Pensacola Fla.
Posts: 590
Total Cats: 191
Default

Cyl 1 and 4 have issues, Have you figured out just why your spec on 1 is so screwy?
What is making #4 tighter than the rest?
BogusSVO is offline   Reply With Quote
Old 02-02-2013, 06:30 PM   #13
Elite Member
Thread Starter
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default

My guess is that Cyl 1 is screwy because I cracked the ringlands on the piston possibly causing uneven wear. I did drive it 1500 miles after the incident.
SKMetalworks is offline   Reply With Quote
Old 02-02-2013, 07:35 PM   #14
Elite Member
iTrader: (3)
 
Join Date: Mar 2008
Location: Granbury, TX
Posts: 6,009
Total Cats: 583
Default

I would take the crankshaft to a machine shop to get checked.
hornetball is offline   Reply With Quote
Old 02-02-2013, 08:39 PM   #15
Elite Member
Thread Starter
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default

I don't really have an option. Going to have to get the crank turned and buy new bearings. Thats what i get =). Would a .0015 clearance be the cause of the inability of the crank to turn?
SKMetalworks is offline   Reply With Quote
Old 02-02-2013, 09:30 PM   #16
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 12,107
Total Cats: 518
Default

What's the taper with the old bearings? Any difference?
curly is offline   Reply With Quote
Old 02-02-2013, 10:21 PM   #17
Elite Member
Thread Starter
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default

I couldn't verify which bearings belong to #1.
SKMetalworks is offline   Reply With Quote
Old 02-02-2013, 11:33 PM   #18
Senior Member
iTrader: (1)
 
Join Date: Mar 2008
Location: Cromwell CT
Posts: 1,107
Total Cats: 48
Default

Did you check rod end play with a feeler gauge, see if something is binding up? What did you change in the rebuild, are these aftermarket rods (eagle). What is the crankshaft thrust(endplay)? You should be writing down your measurments, Plasticgauge sucks *****.
ctdrftna is offline   Reply With Quote
Old 02-02-2013, 11:39 PM   #19
Junior Member
iTrader: (3)
 
Join Date: Apr 2012
Location: Ridgecrest CA
Posts: 448
Total Cats: 44
Default

Are they the stock main studs, or something like ARP?
czubaka is offline   Reply With Quote
Old 02-03-2013, 12:21 AM   #20
Elite Member
Thread Starter
iTrader: (7)
 
Join Date: Jan 2007
Location: Renton Washington
Posts: 1,742
Total Cats: 3
Default

All stock including hardware. I do not have a thrust dial indicator. The only thing that was changed in this build was #1 piston and rod (since the piston on #1 was cracked @ the ringlands), main and rod bearings, and piston rings. I really need to invest in some higher quality measuring equipment. Ill have to check rod end play.
SKMetalworks is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 58 12-13-2017 10:04 PM
Buzzing from driver side of engine bay? (MS3 install) nick470 MEGAsquirt 7 06-16-2017 02:53 PM
Changing from 460cc to flow force 610cc in diypnp 90 Turbo MEGAsquirt 19 10-19-2015 04:23 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 08:37 AM.