My 92 has a decently modified motor, you can read my signiture about the motor but it has cams aswell. Now my issue is that today i was doing my usual OCD walk around and head a small knock in the driverside rear of the motor. it only occurs when it revs up a little then comes back down(i.e. the cams) but the motor i rebuilt completly myself and it only has about 8,000 miles on it. the only thing that i did not rebuild was the heads, other than the cams and valve seals. Now i know a heck of a lot about motors(not to sound like i jerk) but i have no clue if this was typical with older heads on the 4.6 DOHC. the heads have about 117,xxx on them

and ideas

-cheers

 

I think first we have to clarify whether it is a knocking or a ticking.


Greetings!

 

knock

 

Just to make sure.


There is nothing "typical with older heads on the 4.6", except improper handling and maintenance, so to speak, like with everything. And certain additional care, as the cast iron block/aluminum heads need a little bit more attention, they can't be treated like a regular cast iron monster.


Reason I was asking for whether "knocking" or "ticking" is, besides the very often wrongful description, I'm not aware of any knocking noise from the top of the engine. The troubleshooting manual refers to it the same, "ticking" mostly from the top of the engine, "knocking" from the bottom (except certain Asian models, were the oil flow is different, like Honda).


First area it direct you to with "ticking" noise is cams and valve-train (cams if noise toward the front), or crankshaft for "knocking".


Are you using any larger amount of oil? Seen any larger amount of oil accumulation on the rear, or bottom toward the rear of the engine?


Modified motor? Nothing to see about that in your signature, only a couple add ons.


And you have the noise by revving it up without being under load? That sounds serious. Only time I heard about that was on one with over 200k on it, decided to go with synthetic oil, well, the thinner oil film made his car sound like a V10-diesel. LOL Switching back to mineral one solved that issue.


Greetings!

 

I meant to ask you this for a while, and always forget, so here quick:


What color is yours? Is that the frost (blue) metallic?


I'm curious, only a few ones were painted in this (what I think it is) color.


Greetings!

 

yes sir it is frost blue...the only color i like.


i did hear that that was a rare color.

i didnt like that particular color with the landau top though.

oh and the motor has lunati mild cams, throttle body spacer, and custom intake.

 

Hm, again, sorry, sounds serious to me.


Besides your engine already being rebuilt (w/o knowing how professional and complete, and why?), I can only lean toward lack of proper oil supply, or rather something being out of balance/unbalanced rebuilt.


Here's a short explanation of a very common issue, mistakes madenot only when rebuilding engines, but when replacing the head gasket.


Professionally done, it can't just be replaced. The head has to be leveled, to make sure it's still within its tolerances. If it has to be plained, due to taking of material, obviously the length of stroke is reduced, resulting in higher pressure and force when the pistons move. Most common way to compensate for this are head gaskets in different thicknesses.


If not done properly, well, the higher pressure has to go somewhere. The crankshaft pressure relief accomplished through the valve covers will not be sufficient.


There are lots of causes, not only knocking noise, listed due to improper installed head gaskets (as exampled before), too many to list, but this is the most common one.


Greetings!