TheSamba.com :: View topic - Knocking or rattling noise 71 bus engine(SOLVED, rebuilding)

Tue Jan 27, 2015 7:39 am

Hey guys. I've got a new-to-me 1971 Riviera bus with an unknown-history engine that I'm concerned about, and I'm looking for some help to diagnose the noise it's making.

It's a Brazil case and appears to have a fairly recent rebuild, maybe within the last 10k miles or so. Lots of oil leaks, lots of orange RTV everywhere. Here's what it sounded like:

and this is what I found on the 3/4 side, in the #3 intake:

It made good compression:
1 - 100psi
2 - 115psi
3 - 105psi
4 - 100psi

and the dash oil pressure gauge indicated about 20 PSI or so at idle after revving it a few times... before I found the bolt in the intake of course.

I think I'm going to take it all the way down and split the case, and re-bearing everything. What should I look for when the case is split? If it weren't making the knock I would just leave it alone and put everything back together with correct torque and a new gasket kit.. the noise just worries me.

---- edit ----

I couldn't find my feeler gauges last night so I haven't set the valves yet. Is the heavy clacking noise just noisy loose lash?

Tue Jan 27, 2015 11:37 am

Just wanted to bump the thread and see if anyone has any input on the engine noises.

Tue Jan 27, 2015 11:46 am

My input, don't run the engine anymore. It needs to be taken apart. Who knows what the noise is until its taken apart but it sounds like a rod knock to me.

Tue Jan 27, 2015 12:56 pm

a cotter pin can make a hell of a racket

bolts too

Tue Jan 27, 2015 1:33 pm

- Delete -
Double post

Tue Jan 27, 2015 1:33 pm

My gut feeling is to split the case and mike everything to see what's going on... I'm a total noob with these engines and don't want to take a chance on ruining a very nice new Brazil case...
At this point what's another $100 for bearings? Looks to me like there are a handful of good parts thrown together by someone who didn't really know what they were doing... No disrespect intended to the rebuilder.. just making an observation from the mismatched hardware everywhere and the orange RTV they coated it all with.

Now's a good time to plug the case and set up for full flow I guess...

Tue Jan 27, 2015 2:46 pm

open and see, you might have some damage in the cylinder, piston top, cc chamber.
and some metal might still be in there and it could make even more damage.

keep us updated!

Thu Jan 29, 2015 2:19 pm

Took the engine down to just the case and I haven't been finding any happy surprises along the way.
Kolbenschmidt 85.5mm flat-top pistons in worn cylinders
Aftermarket heads
Tons of slop all around on the rod big ends
And then I found .020" of endplay as measured with a dial indicator at the flywheel. I've been optimistic about this engine all along and am still hoping to find a good crankshaft and good case. Going to mic everything either way, since hope doesn't make the bus move by itself...

Thu Jan 29, 2015 5:49 pm

I was gonna say the problem is loose flywheel but didn't bother sine you'd have to disassemble the whole engine anyway.

Fri Jan 30, 2015 5:10 am

Looks like the 'SiliconeKid' pulled half the oil gallies :roll:
hopefully the case will be good?

Fri Jan 30, 2015 5:10 am

Looks like the 'SiliconeKid' pugged half the oil gallies :roll:
hopefully the case will be good?

Fri Jan 30, 2015 5:40 am

Take the flywheel off and your end float shims then move the crank backwards and forwards and look to see if the bearings moves a hair with it. If it does, you are going to need to get the thrust face cut for an oversize bearing. New bearings all round would just be a great idea

Fri Jan 30, 2015 5:43 am

scrivyscriv wrote: Took the engine down to just the case and I haven't been finding any happy surprises along the way.
Kolbenschmidt 85.5mm flat-top pistons in worn cylinders
Aftermarket heads
Tons of slop all around on the rod big ends
And then I found .020" of endplay as measured with a dial indicator at the flywheel. I've been optimistic about this engine all along and am still hoping to find a good crankshaft and good case. Going to mic everything either way, since hope doesn't make the bus move by itself...

Wow, the builder really must own shares in silicone sealant! That stuff has no place in a motor. There are much better products available. Permatex

Fri Jan 30, 2015 8:01 am

I thought this was going to be a gasket kit and new set of bearings type of thing, but looks like it's a rebuild now. Just too much wear and silicone everywhere.
Those oil galleries are going to get the scrubbins of their life!

Also, I measured deck height at .145" which would put my compression ratio about 6.5 - does that even sound right??
http://johnmaherracing.com/calculators/engine-calculator/
using the calculator here I plugged in 85.5mm for the cylinders, 69mm for the stroke, and estimated 52cc's for the combustion chamber with a measured .150" deck height. Seems like 6.5:1 is pretty low, even for a bus engine.

yes, the cylinders were all shimmed

Fri Jan 30, 2015 9:21 am

Huge deck! :(

Fri Jan 30, 2015 4:50 pm

Split the case and got all the guts out today... Found the smoking gun, have a look:

I'll post some photos of the bearing later on... Needless to say I only have 7 of my 8 rod bearing halves.

Fri Jan 30, 2015 5:15 pm

Ouch

Judging by the quality of the build so far, and seeing how you didn't find the other halves of the shells in your case, it's a question whether they were ever there in the first place!

Fri Jan 30, 2015 5:25 pm

I guess I was wrong when I suggested it was a rod knock.. It was two rod knocks lol. Now you get to do the fun part of rebuilding it. You know it will be done right this time around.

Sat Jan 31, 2015 11:12 am

The crank is trash, the rods are trash. The rod that let half of its bearing shell go wore its corresponding crank journal down .030" out of nominal limits.. I could have the crank ground but seeing how black it and the rods are, no thanks.

Pulled out a crank I had in storage from tearing down the Bug motor and re-miked it out at first under. Plan on polishing and using it. I wanted to go with a C/W crank from DPR but I'd rather spend that money towards balancing the engine...

Oh, and the case thrust checked out just fine. Turns out the .020" end play was because of an improperly set endplay. I didn't mike the shims but there were only TWO shims installed.

Sat Jan 31, 2015 11:26 am

It's going to run like a dream when you are finished, you are paying attention.