bad lifter or rocker? video

[6gunn]

I just picked up this 87 GN that has a top end noise for a pretty good price($11,250). The guy I bought it from said that he romped on it to pass someone and afterwords, this noise appeared. Thinking either lifter or rocker. Oil is clean though as well as the coolant. No signs of mixing. The motor has approx 20K miles since a "mild" rebuild, according to the seller. He had a shop do all the work to the car and wasn't able to tell me much other than that the stock heads have been ported and that it was an 11 second car. No idea about cam, type of lifters, or anything. It has a recently rebuilt 67mm Precision turbo, alky and 75lb injectors...so I'm guessing that the motor was built for some power. It also has a 3200 stall, built 2004R, and a Ford 9" rear among other things.

I've never opened up a 3.8 before, so it's going to be a learning process. Should be interesting. If it turns out to be a lifter, I think that will be a good excuse to upgrade to a roller cam setup if it doesn't have one already. Any ideas or advice or recommendations?

Video:

 

[dank GN]

Have you pulled the valve covers? It might be a bent push rod? I’ve have had that same noise acouple times once it was a bent push rod , then a broken rocker arm then the worst one was a complete rebuild to get rid of the rod knock :-(

 

[dank GN]

Or could be a bad exhaust leak definitely start with the easy stuff

 

[6gunn]

Have you pulled the valve covers? It might be a bent push rod? I’ve have had that same noise acouple times once it was a bent push rod , then a broken rocker arm then the worst one was a complete rebuild to get rid of the rod knock :-(

I haven't pulled the valve cover yet. Forgot to mention that it has GN1 valve covers. Are they higher than stock to clear bigger rocker arms or anything like that or is there no difference? Also, assuming the problem is up top and I don't have to remove the heads, can I set up a dial indicator to measure lift on each valve to possibly determine what camshaft is in the motor?

 

[dank GN]

I haven't pulled the valve cover yet. Forgot to mention that it has GN1 valve covers. Are they higher than stock to clear bigger rocker arms or anything like that or is there no difference? Also, assuming the problem is up top and I don't have to remove the heads, can I set up a dial indicator to measure lift on each valve to possibly determine what camshaft is in the motor?

Well you can always pull the oil pan and wiggle the rods and see if you spun a bearing as a last test .

 

[turbo nasty]

Rocker arm, rocker shaft, cam sensor, cracked flex plate, loose flexplate, loose conv bolts, loose balancer, No transfer groove in front cam journal to allow oil to driver side lifters

 

[Pronto]

Pull the valve covers and take a look. Good bet he pumped the lifters. Definitely sounds top end.

 

[BobbyBuick]

bent pushrod or broken rocker easy fix
pushrod could have went through rocker

 

[6gunn]

Well, here's pics of the carnage. This was at the rearmost cylinder on the pass side. The pushrods all looked ok including the one that was on the rocker near the break in the rocker shaft. There is a small indentation left on the mount on the head(in last pic). Does that look like it will hurt anything? Hopefully there's an upgraded rocker shaft out there among our vendors so this doesn't happen again. Also, seems they put it together with ARP studs. Nice to see that.

https://imgur.com/JlIoLxc

https://imgur.com/zJyIE8c

https://imgur.com/jLFmPh0

 

[Chuck Leeper]

TA hd shafts, Earl Brown's rocker shaft supports.

 

[Ed Valvo]

Happens all the time. Good thing you caught it early.

 

[dank GN]

Glad you found it . It definitely sounded like that’s I called it lol . At least it’s a cheap fix could have been much worse as I have experienced

 

[earlbrown]

Yep. Design flow from the factory. Using a flat bolt head to clamp down a round hollow tube is a recipe for disaster. Made much worse when you drill a hole though it then hang the end rockers past the stand with no support.


If you look real close at the other 5 holes that aren't cracked, you can see where the bolt flange pushed a dent down and stretched the metal.

 

[6gunn]

Yep. Design flow from the factory. Using a flat bolt head to clamp down a round hollow tube is a recipe for disaster. Made much worse when you drill a hole though it then hang the end rockers past the stand with no support.


If you look real close at the other 5 holes that aren't cracked, you can see where the bolt flange pushed a dent down and stretched the metal.

Wow, disbelief ensued after I looked at the other 2 bolt holes(don't have the other rocker assembly off yet). How all 3 bolts were tight, I have no idea. Just for S&G, I measured the OD of the rocker shaft with a digital caliper.

OD-.810
Rear bolt hole(the one that broke)-.696
Middle bolt hole-.715
Front bolt hole-.699

 

[earlbrown]

They stay 'tight' because they're tightened down on a spring. Only the bottom 40% of the shaft is supported. The rest of it gets squished down and outwards.

....and if you're calipers are accurate, you verified the shaft is squished. The correct OD is .8125"

 

[BobbyBuick]

if you need shafts i think i have a couple sets

 

[dynoman]

When you get the shafts off , chase out the shaft mount holes with a bottoming tap , then use longer grade 8 bolts to mount the shafts if you use HD shafts and supports .
I had a shaft mounting bolt back out and after a run my car was ticking .

 

[TurboTnZ06]

Hit the shaft with a file before putting a new one on to make sure its hardened.

 

[6gunn]

Ordered the TA hd shafts today as well as their stud mounting kit and some valve cover gaskets. Waiting to hear back from earl about the rocker shaft supports. TA says their HD shafts don't need the shaft supports, but I'd have much better peace of mind with them. Kinda surprised that they don't offer them.

 

[Boost231]

you can get them from RJC. I use to run 6 supports and HD shafts in mine before going roller