MR2 Roadster Owners Club

The Workshop => Maintenance, Problems & Troubleshooting => Topic started by: andyb on October 29, 2017, 21:56

Title: Mysterious Engine Knocking
Post by: andyb on October 29, 2017, 21:56
 m https://www.youtube.com/watch?v=8h60L0PW09A (https://www.youtube.com/watch?v=8h60L0PW09A) m

Checked the big end bearing clearance and the rod thrust clearance, all well within spec so I'm open to any suggestions to what's making this knocking.

I also checked the diameter of the rod bolts and they are all OK but what's the consensus reuse or replace?

Big thanks to Carolyn for all the above specs.
Title: Re: Mysterious Engine Knocking
Post by: jonbill on October 29, 2017, 22:07
Is that from before you stripped it down?
Did you measure clearances with old or new bearings?
How are the main bearings?
Have you checked the Valve clearances?
Title: Re: Mysterious Engine Knocking
Post by: andyb on October 29, 2017, 22:39
The video is from before I stripped it down.
The clearances are with the old bearings.
Haven't checked the main bearings or the valve clearances.
When I stripped it down I found no metal in the sump or oil, had a oil change about 6 months ago and oil level has never needed to be topped up.
Title: Re: Mysterious Engine Knocking
Post by: andyb on October 29, 2017, 22:52
Forgot to mention, the knocking varies. Its never there when I start it up and it comes and goes. Seems loudest at tick-over (when its there). If I hold the revs at 2000 it seems to disappear.
Title: Re: Mysterious Engine Knocking
Post by: Carolyn on October 30, 2017, 07:08
Chain tensioner?  Doesn't sound like a rod.  By 'strip down' do you mean engine out and dismantled, or sump off?  You can reuse the rod bolts, just measure the thickness at the stretch portion (as Jon advises).  Also worth checking valve clearances, and having a good poke around with a stethoscope (all the pulleys).
Title: Re: Mysterious Engine Knocking
Post by: krazysteve on October 30, 2017, 09:09
Have you checked the aux belt tensioner?
Title: Re: Mysterious Engine Knocking
Post by: andyb on October 30, 2017, 10:43
Thanks for all the replies.
Strip down was sump off.
Chain tensioner, Aux belt tensioner, pulleys. Well that should keep me out of trouble for a while  s:) :) s:)
Its done 75000 miles now so checking valve clearances would be a good idea just for peace of mind if nothing else.
Title: Re: Mysterious Engine Knocking
Post by: Carolyn on October 30, 2017, 15:11
Paul at TCB (in 'affilliates' section) has got chain tensioners in.  I don't know how many, but quite a few on here want them, so get one before they're gone.
Title: Re: Mysterious Engine Knocking
Post by: andyb on October 31, 2017, 12:37
Back again! I don't think it sounds like a main bearing but what's the clearance supposed to be. Won't hurt to check as its apart anyway.
Title: Re: Mysterious Engine Knocking
Post by: Carolyn on October 31, 2017, 12:52
Generally speaking, mains don't knock (no reciprocating motion).  However, 0.015 – 0.032 mm (0.0006 – 0.0013 in.)
Title: Re: Mysterious Engine Knocking
Post by: jonbill on November 1, 2017, 06:10
+1 on checking the belt and the bearings on alternator, water pump etc. My other car had a vaguely similar knock that stopped when I reduced the tension on the belt.
Title: Re: Mysterious Engine Knocking
Post by: Carolyn on November 1, 2017, 07:47
Have you got the engine out of the car?
Title: Re: Mysterious Engine Knocking
Post by: andyb on November 2, 2017, 23:48
Doing this with the engine still in the car.
At least after doing all this I'll know the condition of my engine.
So thanks again for all the suggestions, looks like its going to be a case of elimination until I find the cause.
Title: Re: Mysterious Engine Knocking
Post by: Carolyn on November 3, 2017, 08:15
I've sent you a Private Message. (see top right corner of this page).  I must confess I'm mystified as to how you measure main bearing oil clearances without removing the crankshaft and cleaning the oil off the bearings?
Title: Re: Mysterious Engine Knocking
Post by: carolineasb on November 4, 2017, 09:20
I'm afraid to say, the engine sounds just like ours in Oldie  s:( :( s:(  she was fine for a time while we waited to get her stripped or a new engine and then, just when we got the engine we found the dreaded metal filings in the sump  s:( :( s:(

She now has an 06 engine and waiting on a new Cat (hubby managed to damage it during the strip and rebuild  s:( :( s:( )before she's back on the road!