|Topic Review (Newest First)|
|Today 07:17 PM|
At this point, I don’t know why it failed. I measure EVERYTHING when I build an engine, including plastigauge to check for clearances. It’s clear the bearing was spinning in the rod, which can happen if there’s too little lubricant.
I’ll rebuild the engine later. Something will turn up during the teardown and checks.
I am a little concerned about bearing quality. They were sort of hand-wrapped when I got them from OKP. No box, no name.
|Today 06:16 PM|
Originally Posted by DPeterson3 View Post
|Today 05:22 PM|
Spun the #4 rod bearing.
I can still clearly see where the machine shop removed the galley plugs and replaced them after rodding.
Although I drove the engine just a few miles, I was noticing the oil pressure being lower than I like, although the temps were right in the middle.
Good news - the pistons and cylinder head are perfect. So... We'll transfer the head to the ready-spare engine, rather than swapping cams, manifold, etc and having to re-shim everything. We will, of course, clean the head in case any of the shavings from the spun bearing made it through the filter and into the rest of the engine.
I mispoke in an earlier post. My last rebuild failure was when the 2300 wiped out two pistons due to the rear carburetor having a leaky float and flooding the rear two cylinders. The carbs were freshly rebuilt from Alfa1750 in Europe, whose sole response was to send me a fresh float.
Fingers crossed that engine #2 won't have anything tragically wrong. Both engines got new everything. In this case, I'm wondering if it was the oil pump, or a bearing shell not up to snuff. The latter is unlikely. I bought bearings for both engines from OKP. Not cheap.
|Yesterday 05:17 PM|
When I drained the oil, which had maybe 10 miles on it, the magnet had a fair amount of fuzz, and the oil was dark. Neither should have happened in 10 miles.
It’ll be an entertaining couple of days.
|Yesterday 01:34 PM|
If it were my problem I would try to isolate the cylinder by removing the spark and noting any change in the tap.
Old school trick. Just keep the leads loose and when she starts to rattle remove the spark. It should (the noise) change with
|Yesterday 01:22 PM|
|vintagemilano||Quickly draining the oil will tell you if there is anything serious going on in the bottom end. Or even just take the plug out, jamb your thumb in the hole and see if there is stuff on the magnet. Small end bearing, you would have to see if there is any bronze in the drain pan if they have bronze small end bearings.... Hope it's something simple.|
|Yesterday 12:47 PM|
Yup, checking timing & verifying TDC & dizzy firing time costs nuthin' and only takes a few minutes - basics, always back to basics
Decades ago I overhauled the Webers on my student GT 1300 Junior, popped them back on and it wouldn't start...off again, stripped, rebuilt, back on... no start.... off a third time -> what have I done wrong ?? Got gas, got spark....yup got gas & got spark
If you've ever done carbs on a 1300 with the shortest block of the Nords, everything is really close to the inner wing and a bear to work on. Pushed it out the drive, tried a bump start down the road... walked home, fetched Dad & a tow rope... back home he left me to push it up the drive. when I finally got it into the carport he met me at the garage door with a grin and said "does this go anywhere ?" holding the rotor in his hand. Aaaarg, I'd taken it out to give more clearance to my right elbow when wrenching the nuts under the plenum & the manifold & I'd checked the spark by flicking the lead from the coil against it's spade terminal on the dizzy instead of checking at the plugs - too lazy. Popped it back in, touched the key & vroom... lesson learned !!
If the timing is right, the do the plug lead test by pulling alternate leads until the hammering changes - that's the offending cylinder
Holding thumbs that it's a simple fix
|Yesterday 11:24 AM|
We’ll be looking at everything.
My first thought with your dizzy suggestion was “huh?,”. But, then I thought some more.
It certainly sounds like a whacking-on-metal failure of some sort. Piston pin? Anyway, there was a sudden power loss, and the noise isn’t there until some revs come on. Dizzy timing slip will get a check.
|Yesterday 10:09 AM|
Don, check that the dizzy hasn't shifted before you strip the motor down... It could give you the same symptoms and is far cheaper to check than the alternative
|Yesterday 10:03 AM|
Originally Posted by PS70 View Post
|Yesterday 08:32 AM|
|PS70||Bloody French !|
|Yesterday 07:24 AM|
The failure occurred yesterday evening just before sunset. We removed the cam covers, and saw nothing. The engine was warm, so I just called it a day and poured a good glass of Barbera.
I have commitments today, but son will arrive early tomorrow, and we’ll do a few quick checks before committing to pull the engine. He thinks it’s bottom end, but I think it’s top. Either way, it’s so easy to pull the engine and trans, we’ll probably have them on the stand by noon.
Shouldn’t hold me up from making Concorso. Just aggravating.
It idles perfectly without bad sounds. Revving through about 2,000 the tapping starts. It has the classic “rapraprap” of a failed rod bearing, but I’ve got other suspicions.
Watch this space.
First overhaul failure I’ve had since 1989, when a French aircraft engine twisted off a fuel pump drive tang because US gasket paper was .001” thinner than the French metric gasket paper it replaced.
|Yesterday 06:54 AM|
Oh **** !
No wather in oil, no oil in wather ?
Did you yet measure the valve clearance ?
Did you measure the compression into each cylinder ?
|Yesterday 06:26 AM|
|divotandtralee||Might as well put a stethoscope to it..don't you think? Really sorry for the set back. sounds like a stuck valve you might see in the plug hole.. bound up spring ?/ blah blah .. I'd want to go there before I shelved it.|
|Yesterday 06:15 AM|
Well, it’s said that if an engine overhaul is going to go wrong, it’ll happen in the first few miles.
Yesterday evening, after changing the oil and tightening the head nuts, we took a quick test drive. Accelerating up the highway entrance ramp it suddenly went flat and wouldn’t rev past 5,000 RPM. Plus, “taptaptaptap”.
Limped home. No external distress, and cam lobes look ok. Pressures and temps were ok.
We’ll have the power unit out on Tuesday, and my other ready spare in on Thursday.
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