First I’ll start with some background on my engine from hell


I bought the thing last winter as a performance 351W crate engine.

When I put the engine in my truck (it was my 2wd 76 f-100 at the time) the engine would not start and I had a bunch of initial startup problems with valve adjustment. Once I got it running and on the road it ran Ok except it wouldn’t run over 4,000 rpm. After trying a half million different things and adjusting the valves 5 million times the shop said to send it back at my expense ($300). At this point the engine had 7,000 miles on it and had a faint knock…..probably from all the misfiring at higher rpm’s. They told me that the valves springs went soft which was causing the problem….makes sense but makes me wonder if they put the wrong springs in. they also told me that they put new bearings in and polished the crank to remedy the tapping/knocking.

While I had the engine out I actually sold off all the parts off the 2wd truck and pieced together a 76 f-150 4x4 with the money I got. When the engine came back I put it in and proceded to break it in and get the exhaust put on. After that I have been using the truck to move into my new house. On Saturday while hauling then new washer, dishwasher and shelves (a pretty heavy load) I started to notice some engine noise. (I checked the oil level. I was a quart down) added some oil…. But the tapping got worse to a point where it is really annoying. I have 1000 miles on this thing since I got it back and it is tapping…..I am upset to say the least.

The tapping is at a constant tone that doesn’t get any louder or softer with changes in engine load. It is loud enough that it can be heard from 8 feet away from the front of the truck but it is quiet enough that it can’t be heard from behind the truck (I have a loud exhaust) The tapping speeds up in conjunction with the engine rpms. I put a timing light on the engine and revved it up. The taping corresponds to the light so the tapping occurs every other revolution. I then tried to see if it is related to a certain cylinder so I shorted the plug wires one at a time. The sound did not change for any of them. I pulled the valve covers and checked for any loose rockers. All of them seemed to have the right amount of preload. I then used a screwdriver to find were the sound was loudest. It seems to be loudest from the front of the engine on the passenger side near the distributor. I can’t hear it from the valve covers, oil pan, or from the lower sections of the block.

So what do you guys think? Does it sound fatal?

 

Have you checked for an exhaust leak at the head (where headers or manifolds mount)?

 

What a pain! Is the fuel pump on that side. Timing chain might be another possibility. When you say crate engine, can you tell us who built it?

 

The fuel pump is on the oposite side. I tried listening to all the accesories and they checked out fine.


The builder was Golen Engine service in Boston.

The engine has a lifetime warenty....which is why I bought it instread of building it myself.........boy is that a decision I regret!!!!!

By now I could have built one a lot better for the same cost.

I guess it has the warenty cause it NEEDS it.


Once I can pinpoint the problem I am going to fix it myself or find someone local to do it if it is too time consuming.


Is there any quick easy way to tell if it is the timing chain? Can the timing chain may a distinct knock or tap? I always thought that they made a sound like bolts beeing swirled around in a coffee can when they go bad.

 

check the return spring on the fuel pump while you got that out see if you can get a finger in to check the fuel pump cam on the end of the cam shaft for tightness to check timing chain pull the dist.cap rotate the engine with a socket on the crank one way then watch the dist rotor and rotate it the other wayit should stat moving within a couple degrees of crank rotation a loose chain will require more crank rotation to move it

 

It isn't an exhaust leak, it is a metalic tick/knock from under under the intake near the distrubuter. I can bairly hear it from the exhaust side of the head when I put a screwdriver on it.


I am thinking that a lifter has colapes or that the builder put the old lifters back in in the wrong spots and cause a cam lobe to wipe off. does this sound probable?


or is it posible that there is some kind of fatal problem in the bottom end.

I used to have a truck that had rod knock but that was so long ago that I don't remember what is sounded like...that engine blew apart years ago.

Also does the fact that shorting the plugs doesn't change the sound inicate that it is not a problem with the bottom end?


I am really hoping that it is not a bottom end problem!!!!!!

 

Ahhh, didn't realize you had gone that far. It should have hydrolic (however thats spelled), you can try adjusting the valves, often after break-in, you will end up with "play" in the valve train (zero lash for hydrolic)

 

A flat cam lobe usually causes more of a misfire and "burp" through the exhaust. You can also look to see if one of the rockers is barely or not moving as the engine runs.
I'm wondering if one of the lifters is sticking or has excess clearance in the bore, and I don't think that it's a bottom end issue from your description. I would also check the valve guides/clearances.
I have seen numerous cam and lifter bore issues on rebuilt engines. It seems that these are some things that are sometimes not checked during the rebuild.
My suggestion is going back and checking the entire valvetrain - that includes the geometry of the rockers as they ride across the tops of the valve stems. If you have a high lift cam in the engine and the pushrods are not set up correctly, there can be a lot of side loading on the valve stem, causing it to wear in the valve guide.
Good luck!

 

Well I tried taking the fuel pum out and inspecting it. no wear......in fact just to rule it out completely I ran the engine with the pump out......it still ticked.

so I put it back in and move onto adjusting the valves.....again. I loosend them one at a time with the engine running untill it clattered then tightened it down junst untill the clattering stopped, then I put a nother 1/4 turn on it. Each time it did this there still was the tapping going on in the background.......so now I am really confused on what this could be.


I went to a local engine builder and asked them to look at it .... they brought out there fance stethiscope (that thing was really nice) and they found that.....same as me that the sound is coming fron the front of the engine but couldn't pinpoint it. they suggested that a lifter may not be spinning......but I would assume that tigntening the rockers would stop the sound and it didn't.


Well on the bight side I broke a u-joint wile pulling out hard.......so that means I get to tinker with something other that the &*%$*@! engine.

 

A word about engine warranties............it's fairly common for gyppo rebuilders to offer fantastic warranties that they have no intention of backing up.
Here on the west coast I know of quite a few rebuilders who went out of business as soon as the warranty claims started to pile up. A couple of months later, they're back, same place, same people, only under a different name. And the cycle starts all over again.

As far as your noise, the rebuilder probably installed a reground cam. If it wasn't ground right the lifters won't rotate in their bores. Just one possibilty.

 

The cam is a brand new comp cams XE268 so it is not reground but it seems like the lifter not spinning is a real posibility. I drove the truck another 400+ miles and the noise seems to have stayed the same.

I had gearhead friend listen to the thing and he originaly thought that it sounded kindoff like a rod but then once I showed him that the tapping doesn't go away/change under load and showed him that it stays constant through out the rpm range he became stumped too.

I tried pulling the plug wires once again to see if the sound changes.....yet again no changes whatsoever.

I guess I will drive it hard untill something breaks or wears out....then I will know what caused it....unless someone can diagnose it in the meantime.

the truck makes awsome power!!! I raced some guy in a ricer the other day and blew the doors off him.. this thing really hauls when you wind it out....sounds awsome to.... I have no way to officially clock it but the 0-60 is around 6 seconds....not bad for a nearly 7,000 pound 4x4 with a smallblock.

 

If a lifter is not spinning, two things will happen that you can see clearly. 1) The pushrod will not be spinning either. Run it with the covers off, and look to see if the pushrods are spinning. 2) The cam will NOT SURVIVE PAST THE BREAK IN PERIOD. If a lifter is not spinning, say hello new cam/lifters/bearings. Seriously, they go flat REALLY REALLY fast. A few miles with a stalled lifter and you get to send the engine back to them again.

I doubt it is that, but if you do find that it is, and it is still running, you still need to replace the cam and lifters, and look carefully for galling/wear which will throw metal shavings into your oil supply. (Hello bearings and hot tank).

My bet is pushrod interference. Pull the rockers and look over the pushrods and rockers for any marks. I will bet at least one of the pushrods is sharpened on the end that rides in the rocker.

OR
Have you checked out the distributor bushing? How about the dipstick clattering on the crankshaft (seen it happen), how about timing cover rubbing on the chain? How about valves hitting the pistons (forged pistons or cast?) Oil pan clearance to crank? When they re-rebuilt it, did they change the cam bearings? Accessories on the engine?? water pump, alternator, power steering pump?

 

I checked the pushrods and roller rockers already they are all ok and the oil is still nice and clean. So I guess that maybe I can rule out the lifter cam thing. also while I was adjusting the valves I noted when I backed out the rocker untill it clattered the ticking was still going on in the background for each valve.


I checked all the accessories they are quiet (ran the engine without them, sound was still there)

I took off the fuel pump and ran the truck.....sound still there.


the pistons are cast psitons (9.5:1 comp ratio)

new cam bearings were installed......and I thought that worn cam bearings didn't cause any sound......just broke the cam....


I know I didn't dent the oil pan so I don't thing that that is it. plus it only taps every other revolution not on evertone so I doubt that it is the dipstick or oil pan.

The chain hitting the cover sounds like a real posibility....
as does the distributer....

tonight I will get out the stethiscope and listen to the timing cover a little better and pull the distributer....

thanks a lot for your suggestions!!!!! I never would have thought of a bunch of them.

 

Regarding the tapping noise, have you identified the problem?
Two days ago I have exactly the same noise symptoms, also
without changes when removing the plug wires, however my
noise seems to originating from the rear of the block and this
is a chevy 5.7l(sorry I know this is a Ford post). I will buy a stethescope tomorrow and
see if the distributor could be the culprit.

 

I still haven't found out what is causing it yet.......... if you find anything out please let me know.