Driving in the rain and pulling off a stop sign truck loses traction and RPM's go high. When they come back down the truck makes a very loud tap when you accelerate. Idle has no indication of problem or noise short of a slight miss.

 

I'm assuming you ran it pretty hard to the top. They're OHC which doesn't have pushrods. But I'm not sure it could be a con bearing either, because every one I've ever come across has knocked even at idle.

But I could be wrong.

My experience with the 2.3 is limited, I had a 2.3 turbo coupe, fmic, forged bottom end, stock top end, I beat the hell out of that thing and didn't see anything wrong with the head other than the burnt exhaust valve I knew was already a problem. The head proved tough in my short experience with it. That car didn't last too long after the head was redone and teh boost was kicked up, It proved to be pretty damn fast and dangerous, I loved 3rd gear sideways on the dirt roads back home in NC.

I had it just under a year. Tore it down once.

 

Thanks, Yeah I remembered this one was SOHC. Too pissed off to think. I have to rev it pretty decently (above 3k) when at idle to get it to make the noise so it's hard to listen and isolate it. It will tap loudly under any strain accelerating no matter what the RPM. It's more high pitched than low knock which is why I was hoping it was in the head, but it's SO LOUD it's like a con rod bearing with the intensity of the hammering sound.

 

Ok here's the video's. Might help us a bit. I have flowmasters, but you can hear the noise well.

 

my vote is gonna be valve tap or rod knock...if it was a spun main bearing your truck wouldnt be running more than likely...motor usually locks up...hard to tell in the video but if it was a rod knocking it would be very deep and rythmic

 

It runs fantastic, short of a small miss..... just sounds horrible when I put a load on it. Noise is very high pitched and metallic. It sounds like a valve, but I never knew a valve could be that loud. It was echoing off the houses as I brought it home and sounds exactly like a hammer smacking the engine, but not low toned.

 

does it sound like its coming from the top of the motor or from down low?

 

It sounds like you got a valve chattering.
whatever sound coming out the engine is gonna be magnified x10 from the Flowmasters you have. Kinda why i don't have any.
Anyways. I find that Lucas Oil Fuel lube/stablizer junk you get at autozone for like 5 bucks usually makes mine a more quiet an livable level.

 

The problem is that when I am at idle I have to rev it so high I can't hear where it's coming from and I can't hold it there at that level of RPM. It really only produces the sound under load.

 

On the video it does sound like a valve chattering, but in real life it is incredibly loud and powerful tap. I'm not a tech and I'm not the best person to ask about engine internals, but I'm 35 and have had roughly 70 cars so I have heard plenty of valve chatter and this thing is just flat out impressively and incredibly forceful tapping that similarly resembles the rod knock I had in my Mitsubishi Eclipse when I was in my teens, but the difference is that it is very metallic and high pitched LIKE a valve so it is screwing with me.

 

it sounds like valve clatter to to preignition, I've heard it on my 96 2.3 I thought it was just bad fuel on tried premium and it got a little better but didn't go away I finally got tired of hearing it and hooked up my scan tool and found out the ECM wasn't retarding the ignition enough, It took a while to find two small vacuum leaks and a map sensor on the very edge of it's range, it all added up enough to make the ECM think the engine was under light load and advance the timing for better fuel economy I hope this helps

 

Had a chance to mess with it a tad more today and have these following observations:

- Engine does not knock at any RPM unless I get them REALLY high which is just simulating a light load on the engine which is when it DOES knock at ANY RPM..... if it has a load on it.

- Engine has a miss and can see the miss in the engine as it lopes like it's missing on one cylinder (which I am sure it is).

Doesn't this sound more like the head than the block? Only makes noise under load, not at any RPM. Has a loping miss to it.

 

The valves don't have anything about them that stands out to the naked eye. They are also not any louder with the cover off so it might be the bottom end. I still don't know.

The two biggest problems I had on this are

#1 - I didn't have a towel to cover the cams which leads me to......

#2 - I was the only person so I had to do this on my own. This inevitably meant I had to start the truck, no valve cover, no towel, and rev from under the hood with oil going everywhere. Life is like that sometimes. :)

 

Any excuse to degrease is a good one. Was back together perfect and cleaner than before in an hour.

PS- oil pump works marvelous.

 

I have this same problem on my old Dodge and it seemed to take forever to find.
Ended up it was the exhaust manifold gasket blew out on one cylinder. Sounds just like a rod knock.
Finally noticed the light soot around the blown gasket.

 

LOL, man I wish that were the case here. Too much high pitched metallic clanging in my case, but boy oh boy do I wish that was my problem.

 

pull the head off and go from there.

 

I will be pulling the head off...... because I am blown between #1 and #2 (if you count from the front). I got 140 lbs on the back two cyls (against the firewall) and 75-ish on the front 2 cyls when I did a compression test just now.

I've never used a compression tester so I followed the instructions and removed ALL the plugs. Apparently those instructions weren't written for this engine........ Got nothing. So after putting the intake side back in and testing on the exhaust side (one at a time) with the tester I came up with 140/140/85/75 from back to front.

Looks like the reason it is clanging under load and not at idle is because of #1 pushing on #2 between the gasket. Didn't hit a water jacket so no signs of a bad head gasket until I put it on the compression tester. Don't see how the valves could regulate the compression even in this engine so looks like a head gasket to me.......? That's why the harder I load it the louder it hammers.

The front two cyl plugs were dark, but firing.

#1 (firewall)
#2 (from firewall)
#3 (2nd from front)
#4 (front)

 

The only ones that look bad there are row 3. maybe a little bit in column 2, row 2

 

You can see how cold the ones in the front are if you get closer

(on left)

PS- how many people think the head might need to be shaved at 149k?

 

So what did it look like when you pulled the head? Do you have it back together? How does it run?

 

Completely blown between 1&2, partially blown between the rest. New Gasket, TIming Belt, runs like brand new. Paid a guy $370 to do it all, but in retrospect I shouldn't have gotten lazy and I should have dine it myself. It's just not that big a deal to do.

Gonna test it out here very shortly and take a 7 hour trip NW.