Man, she was running just great this past Friday and Saturday. Running several hours both days on the highways and byways.
Then on Sunday afternoon she started having a quiet little metal hammer ring whenever I pushed hard on the accelerator.

As the day wore on, the hammering got louder and more metal-like! I'm talking a real loud clacking hammer whenever you hit the pedal. Once you are cruising at speed and not pushing on the pedal, the sound is not there and the car drives fine.

But as sooon as you ask for a little power with the pedal she starts clackity hammering away!! Man, I had to limp home and put her to bed. Yesterday I verified oil level (new oil and filter last month) and checked everything obvious, but five minutes after cranking her up the hammer sound kicked in again.

Can't tell where its coming from, but it seems deep down in the block. It is nothing loose or external to the block itself. Give me some thoughts and ideas here friends. I am not an engine block pro by any means. I figure a compression test would be as good a place to start as anywhere, eh?

Could be a rod knock. I'm no engine guru either, but it wouldn't surprise me to find out that's what it is. How's your oil pressure? Thick oil upon startup might reduce the amount of knock until it thins out as it warms, thus allowing the knock to become more noticeable. I hate to be a naysayer, and I hope I'm wrong, but this doesn't sound good, John.

Nash, duzn't sound like you had a good weekend, I had a old GMC jimmy that kinda made the same noise as you stated and it turned ot that I droped a lifter but I never drove the truck down the road as you mentioned it would clear up at cruising speed. Either way look on the bright side, this means you get to go grab a few 12 packs and call the friends up for a good evening of turning the wrenches.

Do you have a lot of vibration? I've had water in the gas in our old Barracuda with 10.5 to 1 compression. The car would barely run if you tried giving it the gas. It knocked and backfired because of the high compression. In our pick up I got water in the gas and I thought that I had cracked the crank. The mechanics thought the same thing. Also, they thought the fly wheel was coming loose. I got the water out of the gas and it started running fine. A third time we actually had the electrode burned off in the Camaro we used to have. Our friend that delivers fuel, warned us that if there is a fuel truck filling the tanks at the gas station, don't buy gas there because he has the tanks all stirred up and the water isn't on the bottom of the tanks any more. Maybe this is a possibilty?

That's a rod knock. I'd bet $50 on it. There's only one way to know for sure.

John, say it aint so? For once, I hate to agree with Q, but as usual, I'm afraid he may be right. You could check around and might find some one who can analyze your oil filter and oil for any particles such as bearings giving out.

But either way, you'll have a little project ahead of you as you'll have to see what it is either way...

Wish I was close by, I'd help with the job and the beers in a heart beat! Hang in there, and talk to Q about how you want to proceed...
(this is where the fun begins)

Maybe it's time to bring up Q's favorite engine combo threads?

Were here for ya - Brett!

Sorry to hear it John, Hopefully it's not a rod.

Like Q said, it's a rod bearing. Fix it before it goes through the block!

DANG NASH.I GOT A GOOD RUNNING 350 YOU CAN HAVE IF YOU WANT TO COME GET IT AND PULL IT.IT IS STILL IN THE CAR AND YOU CAN HEAR IT RUN

rod bearing (s)... I had that happen in a MB 180 in 1969...kept driving it carefully to get back to where I came from....suddenly rear wheels locked up....managed to slide into the grass on the side of the road...
DONT drive it!

I knew there was a reason I didn't buy this 455. It's just for Nash!

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=160063872668

Easy way to check if it's a rod/piston.
With engine running, pull one plug wire at a time.
If it doesnt happen at idle, just barely rev it. The bad one will get quite without spark.

Yep,sounds very much like its a rod bearing- been there. Its common for Pontiac V8s.
DO NOT START IT AGAIN! A metallic sound means metal to metal contact, and every revolution means more damage. If you have a #s matching WQ HO motor, it is definitely worth rebuilding, and not too difficult. You can do the single rod bearing for less than $100, but while the motor is out, it's your opportunity to rebuild everything- then you'll get another 200k miles, if you're reasonably nice to it..!

If it's any consolation Nash, I'm down for the winter too now. These cars are just too valuable to chance anything (IMO).

Good luck!

John,

I agree w/the rod bearing. I had to fix mine this past winter. Send me a PM w/your phone number and I will give you a call. Might even be able to come down and offer some assistance.

Tom

rod knock. likely #1 or 2 rod (s)

Well then I think it's unanamous.
Best thing to do now is pull it and have it completely gone through.

If I lived in a climate where I could drive my 1st gen year round, I don't think I would be twittling my thumbs waiting for the engine to get freshened up. I would buy a running engine and swap. In a few hours I would be up and running.

Got a 71 GTO motor with your name on it Nash..

Very cheap and nice to have a back up as to not blow up your numbers matching block and lose 40% of the cars value.

Yes, I said 40%...

Well, I must say I'm glad there are smart folks here to help. I guess the block is coming out without me tinkering around and taking any chances.

Trmjr1 (Tom), number is 931-378-2060. Call when you get some free time during any evening this week. Anyone with thoughts and ideas can always call. Half the Army has my cell number so theres no reason to hide it from friends here.

I've never had to pull this engine before to hand over to a shop, so this'll be a new and wonderful adventure for me....CRAP!! Maybe I'll take a crack at this myself with a little help.

Jeez oh flip I'm mad! But.... then... I think about how good life has been to me and my loved ones over the past few years...okay I'm fine now. And I finally got a response from Banshee (after 12 long months), so I'm okay.

Jim/Terry - I'm thinking along your lines of getting an interim block while the original gets a workover. I'm open for thoughts and leads from anyone on that idea.

Thanks for the analysis, gang. A rebuild is probably overdue on this engine.

John, I'm sorry to hear that! I KNOW the feeling!!! My motor is coming out tonight.....everything is disconnected and unbolted.....just have to pull it for my own tear down....getting all new rod AND main bearings. I think I hammered the rode bearings when I was playing with timing....detonation will kill them every time.

I never heard a knock or a tap, but this thing is so loud it would be near impossible to hear. The stuff floating around in the oil was definitely bearing material.


Drew

Could also be a worn down lifter...

Pull off your valve covers, and try to force down each lifter.. -If one of them is loose/very soft -that's your luck..

-Just my two cents on what to check before you rebuild the whole deal..

i really hope that's all it is, pal..

Drew, thats an interesting coincidence. As you all know, I was doing some major distro/timing experiments last month.

And the oil/filter change a few weeks back did have a glimmer of gold/silver in the old stuff. It wasn't too obvious so I didn't worry about it.

YOW Any gold/silver stuff is real bad!

gold / silver stuff COULD also be a worn down lifter/cam ...

Ditto on the RB, I'd first check the drain plug / filter and see what metal fragments/powder there may be.

How many miles does that 400 have on it? if you need to pull her, at least it isn't the summertime when you could be out cruising.

As Brett said, if both of us were closer we'ed be down to help in no time and to sample some Shiner Bock or better known as liquid wrench!

Don't get me wrong here sports-fans. I'm not talking about chunks or pieces of metal. I've seen that in helicopter and airplane oil.

I'm talking minor dust glimmers when slowly draining the contents of the oil filter. I've always done that procedure, and I've seen those dust glimmers in many cars oil over the years.

Cut the top off your oil filter, cut the paper medium away from the metal core and stretch it out like an accordian. If there's "gold" in them thar folds ...

Nash dont sweat it i have 500 miles on my engine and its out and torn down right now.I am playing with a few things like cylinder wall thickness and different rings as well as playing with windage trays and crank scrapers.If you need a 400 short block i could probably hook you up with one for you to rebuild or put one together for you although shipping could get a bit pricey.Hey would they let you put the short block on a blackhawk? Maybe you could fly up here and pick it up...just kidding. good luck with whatever repair you do on the ol' bird.


Jeremy Wyborney
http://firstgenfirebird.org/show/closeup.mv?CarID=790

Glad your over the initial 'shock" and besides the winter is a good time to be down as JM says, no sense running er when it's too cool out...not even easy on the upholstery!

Get some bock in the fridge and we'll be right down

Nash, you,re awfully close to Butler Performance there in Tennessee...

Here is an option for the second motor:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=001&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=110069338822&rd=1

Cat, that seller spent alot of money on cans of silver paint spray didn't he? I would have at least taped up the spark plugs.

Buy this one and you'll never even want to bother with the 400. Your car is worth just as much with your original engine on the side just the way it is. He'll take $3500.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=160063872668

What about this company, eh? Wonder where they get the donor blocks from.

http://www.theautochannel.com/autoparts/rebuiltbestpontiac/itemklm_599oy_6.html

That would be worth checking out. I would ask them compression and valve size.

Nash, ya can't buy that 455, I'll never keep up with ya!

Not to worry Dave, its a bit more than I'd prefer to pay right now. I have the right original block, just need it rebuilt and another nice in-between-motor to get me around for a few months.

It will cost you more than what you can buy the 455 for to rebuild your original engine. Buy the 455 and stop the bleeding! OR Buy that new 400. Either way, if you keep it simple the power plant will last you a very long time.

I didn't ignore the recommendation to check the lifter or the cam. I have already done that. I'm running a solid cam and solid lifters. They look to be in EXCELLENT shape.

When I pulled the pistons and rods I noticed 3 of the 8 were showing signs of wear on the uppers showing a little copper, but they were pretty smooth.

#2 and #3 MAIN bearings were another story. Crank will need to be cut and polished. #2 and #3 were pretty chewed up and scored.....resulted in scored crank journals, too.