1500 ENGINE NOISE

[80spit]

HAD MY 1500 SPITFIRE ENGINE OVERHAULED NEW BEARING, HEAD REBUILD ETC, STILL GET LOUD LOWER ENGINE KNOCKING ON FIRST STARTING, IT OES AWAY IN A FEW SECONDS, ANYONE KNOW IF THIS IS NORMAL FOR THESE ENGINES? OR DID WE FORGET SOMETHING? /ubbthreads/images/graemlins/iagree.gif

 

[Dave Russell]

My best guess is that something is delaying oil pressure build up when it starts. As soon as the oil gets to the parts it fills the normal clearances & the noise goes away.

A likely suspect would be the oil filter can draining back when the engine is shut off. the anti drain back valve in the filter may not be working.
D

 

[AltaKnight]

Did you pop the pistons out and inspect whilst in there?
Sounds a lot like a little piston slap, common thing and not really a problem if it goes away fairly quickly as the engine warms.

 

[80spit]

Thanks folks, appreciate the replys, pistons were checked during tear down. this noise sounds low in the crank area. Would the thrust washer cause this,a knock comes back at around 2700 rpm on acceleration. It sounds like a single knock then unlike the start up when it's more like a diesel.
Haven't had a chance to check the filter yet for leak down.

 

[AltaKnight]

Sorry, can't see the thrust washers making that kind of noise.
Did you replace rod bearings, mains or both?
Did you measure the journals with a micrometer or use plastigage with the new bearing shells to check for bearing clearance/wear?
The crank might also have been machined undersize at some previous time, if you then installed standard bearings there would be room for knocking until the oil pressure got high enough to possibly quieten it down.

 

[waltesefalcon]

Did you have the crank turned? Another crank possiblility is that you could have a journal thats out of round and knocking, untill oil pressure builds up to queit it down.

 

[trboost]

Parts that have a loose or sloppy fit may knock on start up until a film of oil coats the surface. I'm assuming you did not use forged pistons, as these do slap on startup.
The fact that the noise returns at higher rpm's is disturbing. If it comes to a tear down , before you go to deep pull the front cover & look over the timing chain & tensioner.
Also look for other tell tale signs of a problem, oil pressure readings when hot, use a magnetic oil drain plug, drain the oil & examine the oil & cut open the filter . Check for motor bits, the color and material may tell you whats happening.
good luck