ADVICE NEEDED **Engine Knock**

[AZMSP84]

Hey eveyone, It's been a while since I posted. Mainly because my Speed has been down more than its been running. I just got done finishing the replacement of 2nd gear and I'm getting ready to sell the car. I forgot about the knocking noise upon startup so I had to look at that. I had a feeling it was rod knock so I tore off the oil pan and inspected the bearings. The bearings don't look badly worn, no copper showing and none seem to be spun. I did find two of my oil squirters in the pan when I pulled it but nothing else. Any ideas of what to look at. I measured the crank end play and I'm within specs. Thanks for the help, its just that I don't want to put the pan back up and find out it is something in the bottom end and have to tear it all out again.

Oh BTW the knock is on a cold engine for about five minutes until it gets warm and then it is almost inaudible. Thanks again!

[orng1]

Is it everytime or just from the first time that it hadn't been started in a while? What oil are you using?

[JDM Sam]

its from your oil jet nozzles being chopped off. what pistons are you running??

if you have forged pistons and no jets its going to sound louder b/c the oil isn't getting sprayed under the piston crown area. you'll have to wait till it warms up and oil gets circulated through. i would fix the problem on why it broke your jets nozzles off and replace the jets.

[AZMSP84]

The problem happens every time. It's been doing it for a while I just decided to ignore it, but now its time to sell and a new owner won't be as forgiving. I was running just normal 10w-30 but tried some 20w-50 to see if the knock lessened. There was no change with the oil so I switched back. The motor was a reman motor and its running stock pistons. I'm not sure why they broke off I can't see where they could've hit the piston.

So your thinking that the lack of oil is causing the excessive noise from the pistons on startup?

[SeR_Cyclops]

i really dont understand why our oil jets break off? i mean wtf poor engineering. /threadjack off:

[mspHtown]

i really dont understand why our oil jets break off? i mean wtf poor engineering. /threadjack off:

its not mazdas poor engineering. its the machine shops not pressing the new squirters in entirely or the pistons not clearing the squirters (maybe they clear but when they heat up and expand they can then come into contact).

[SeR_Cyclops]

ok i see so its just something that is over looked.

[AZMSP84]

I figured I should post what ended up happening with my car. I know I always see threads started with a problem but never a solution. As you can read, two oil squirters were lying in the bottom of my oilpan and I had a pretty good knock upon startup for about 5 minutes. I ended up putting new squirters in. I tapped the old squirters with a 10-24 tap and used a 3 foot long piece of thread-all to screw up into it. There is a check ball in the oil squirter so make sure that finds its way out of the engine or else your in for some serious problems. For one of the squiters I was able to attatch vise grips to the threadall and then pound on them with a hammer. For the other one I had to use a slide hammer with an attatchment for vise grips and grab the thread-all as close to the squirter as possible.

One I got those out I reinstalled the new squirters and clocked them like the others. Then I checked the clearances. Well it turns out the the #4 piston skirt was hitting the oil squirter. Upon closer inspection I found that the piston and rod was installed backwards and the notch for the oil squirter was on the wrong side. After much fanagling I was able to turn the piston and rod around in the block without removing the head or the crank. I replaced the rod bearings for the hell of it but they were not abnormally worn. I reinstalled everything and started it up. Noise is all gone, no more worries. Hope this helps some people out.

[shane02pro5]

A bigger help may be to let everyone know who did the rebuild on the motor so they can be avoided!!?

[low_psi]

Sounds like piston slap. Did you always let the motor warm up before driving and boosting?

[AZMSP84]

It didn't seem to be piston slap, the cylinder walls had no abnormal wear at all. I checked the wear of all the cylinders and they were all the same. The engine has 55k miles on it and everything still looks good. The engine was rebuilt by flatlander racing/importperformanceparts.net. The only reason I noticed it was because I saw the skirt on cylinder 4 was lower than the others and when compare to the other side it seemed to be turned around. The rod was installed on the piston correctly because the rod bearing notches were also on the wrong side of the crankshaft.

Also, I have a remote start on my car so its almost always warmed up before driving.

[low_psi]

Sorry, I missed the post you made earlier today.

I have seen damage to the top of a piston and cylinder wall that is only visible once the head is removed. Obviously thats not the case for you though. Glad to hear you got things figured out and running 100%.