Ok i have a forged 355 with stock heads. I had the motor built a little over 2 years ago if not 3 years. Never had a problem with this motor ever. Recently i have been getting bad overheating. Found out the thermostat was sticking closed. The car was overheated quite a few times. Well after fixing the thermostat about a few days later my car starts making a odd grinding type of noise. I thought it might of been a blown headgasket. So i end up doing all the checks and when i took my PCV tube off from the vavle cover/ throttle body i saw that there was chocolate milk liquid in there. Ok so i thought i found it, blown headgasket.

Before i get into taking apart the motor the noise i was hearing didnt sound like valvetrian problems. I honestly beleive its not a failed lifter cause that would cause a metal to metal tapping sound. Ive heard failed lifters before and this isnt it. Upon further inspecting i get underneath the car and listen and its deff coming from the bottom of the engine. My thoughts could have been the oil catch can and baffle i put in the oil pan, could have come loose and the crankshaft is hitting it. Well the noise is only happening during idle at around 950-1000 rpms. When given throttle the sound goes away. I did drive the vehicle like this and noticed no loss of power. It only makes this louid grinding noise during idle.


Ok back to the blown headgasket. I tore down the engine and found more chocolate milk in the intake valley/lifter valley. Took the heads off and noticed driver side was ok. Passenger side headgasket you could tell had a problem with it. It was very very birttle and broke when i barely pulled it up off the block. Inspected the heads and had them taken in and resealed valves and surfaced them. I had a buddy whos buying the car from me work on the car while i was at work. Supposidly he did pull the lifters up and they seemed fine. We put the engine back together and started everything up. Well same problem. The loud grinding noise at idle coming from the bottom side of the engine....


After letting it run and going through all the problems a over heating issue would cause we decided it could either be the oil pan baffle/catch can came loose or a spun bearing? I would of never thought a spun bearing would make a grinding type of noise during idle but when giving throttle it dissappears like nothing has happen.


Any thoughts would be grealty appreciated. We have not taking the oil pan off yet, but plan on doing it this week/weekend just to check the crank and look at the bearings. Sorry for the long post, but im lost on this project now...

Thanks....Randy

 

Sounds like you will find your answer this weekend. Nothing I can think of but pulling the pan.

 

UPDATE:::

I sold the car to a buddy cause he really wanted it. I told him to actually drop the pan and look from there. Well him being a hard headed idiot he pulled the complete engine out thinking it has to be rebuilt cause its a spun bearing or bad connecting rod. Anyways long story short last night we get the block out of the car and he takes the pan off. I was very anxious for this moment cause i had an idea it had to be something in the pan. Well pan comes off and the 1st then we notice. The pickup screen has broken off the pickup tube somehow. Upon further inspection we find the 2 out of 3 nuts holidng the windage tray has fallen off. I said theres the problem you dumbass. What did i keep telling you, pull the pan pull the pan?. Didnt listen.

So im my theory the nuts problably came loose and hit the pickup screen and caused it to come loose. Then from all the pressure swishing around it eventually broke off. During low rpms the windage tray was probably pushing back and forth causing that metal to metal sound. Or could of been the bolts or even the screen being swished around. The only good thing that came out from taking out the block was that he discovered there was only 2 bolts holding the transmission to the block . Thats not good. Im not going to blame the previous shop who worked on my car, but im pretty sure i know who it is that didnt put all the bolts on. So now after all this he has to replace basically brand new head gaskets, oil pan gasket, header gaskets (he ripped one), intake gaskets, and water pump gaskets.....

So theres the problem that has been discovered by taken the LONG way out!

 

Kind of funny someone decided they just was not worth the hassle I recall putting them in.

Glad you found out what the issue was.