View Full Version : knock/ping/marbles- Help me,any ideas?
05-20-2005, 08:05 PM
I've got a problem.. Finally go my project truck with the new 400 in it on the road and now I have an issue. Seemed to start mildly at first... here's the deal. Set 10 BTC, and the carb set up wrong, on it's first drive out I heard what I thought was a rattle of some kind. The performance sucked, adjusted for good vacuum( 18+ lbs), adjusted for 14 BTC and took it out again. Performance was better, but the rattle gets worse. Should be 8 or 8.5-1, new 670 truck avenger, Weinend single plane intake, headders, duals, msd coil, stock dist& box. I set it back to 10 BTC..other then the performance getting worse..no change in the rattle.
Doesn't happen at startup, and if you drive it a block or two when cold it doen't do it, even under load. Doesn't ever do it at idle, but once you get it even a little warm, it does it loaded or unloaded when you rev it up. Can't seem to figure it out.
Only happens after 1700 RPM. Seems to happen a tad less under full load, but consitent under partial load. Gets real bad off the gas 2000-3000 RPM Range. In the cab, sounds like bottom end ( god I hope not). Outside, couple friends/fellow engine builders say it's not deep/metallic/thud or low RPM enough to be bottom end..one suggested dump gas and run 94 octane ( just tried that tonight, no dice). Other suggested possible valve train ( although I thought that would be more of a tick). Sounds like a rattle, like marbles in a tin can going round.
2nd to the first- she still runs real hot. Going to buy another set of mechanical guages this weekend, and try to get a better handle on things..the set I had just popped the oil line( so I know there was pressure..lol) and the water never worked right for some reason.
Either way with a good antifreeze/water mix, well bled, and no stat ( same with one in , did it both ways) it pings,bubbles and rattles like an old steam radiator they used in houses... This can't be a good thing either.
Anyone have any ideas for me? Going to change the oil out tomorrow with soemthing thicker but I am sure that will not help things much either.
05-20-2005, 08:13 PM
If this is a fresh rebuild and its overheating there is a possability the head gaskets are on wrong blocking coolant flow through the heads. this would also make fore some serious pinging.Just grasping at straws here, but I did run into a situation like this years ago.
05-21-2005, 01:07 PM
The motor was built 10 years ago, run a bit then pulled. Got it off an engine building guy- had about 10 motors stored in his shop. He is more of a chevy guy so this one is not as valueable to him. I am beginning to see maybe why it was pulled in the first place. It sat on an engine stand for years before I bought it this winter, pulled it apart. All looked mint/new/clean- no wear and little carbon on anything suggested it hasn't been run much. Had BN 2WD headers on it, 2wd engine mounts and a 800 Double pumper ( god knows why) so I let him keep that.
Put it back together with new gaskets. Everything seemed in order at the time.
One thing i've been asked that I think I am sure of is if the head gaskets got on the correct side..( if not they may be blocking coolant flow. ) I mean I think I did..kind of a hard thing to check now..lol.
Timing seems to have little/no effect on this POS as far as this "knock" goes. You would think so..but doesn't seem to. It sure has an effect as far as perfomance goes though. The vacuum advace works/hold..but have not checked how fast the mechanical advance comes on at how many degrees that it does.
As for the compression..the things been done 30 over, but dished pistons so nothing fancy.. I thought stock 8 -8.4 to 1. In case I was wrong..I gave the 94 octane a shot.. still no difference.
My first bad was only pulling one bearing cap... they looked new/spec out ok..so I just re installed it....maybe should have checked em all.
Going to try and run with the vacuum pulled off plugged and off the distributor see if that has any effect. As stated I could pull it to recurve, but again I am not suspecting that is the knock issue.
It's looking more like pulling either the heads and checking the gaskets ( if she is getting that hot that could cause the detonation issues) or the engine and start over. If I do that, guess I will do the 9:5 to one badger pistons I wanted to try in the first place. May as well go all out if I am going to do that. OR...dump the 400 in favor or a 460...but that would mean another intake, cam etc as well as headers and engine mounts. Bummer
05-22-2005, 07:32 AM
460 all the way...probly similar gas mileage.....check dist. to see if its seized from sittin.....maybe too lean in the carb?....waterpump not workin...ive seen an impeller come off before....rad plugged...too hot...........like you said check head gaskets....if the rad is producing tons of steam....make sure all air is out.....compression check?crack?....did you have the cab heater on when bleeding the air from coolant?........must be on........just throwin some ideas out there......does it start freely or labour when you turn it over?....if so maybe a crank or rod bearing.....let us know.....good luck
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05-25-2005, 02:04 PM
Bought another set of gauges to check to see if the others were wrong. Possibly, but at least they are consistent. Temp readings when it makes the bubble/rattle and "ring" *( like an old house radiator) that made me think it is overheating.. seem to happen long before you would think. They read 100-160. I am beginning to think the mechanical gauges are not the way to go.... but as I don't have an infrared heat gauge...I can't verify the accuracy. Either way, oddly enough after an hour drive today, and it heating up to 200-210... when I stopped at home...there was no bubbling/rattle/ringing.... WTF? I had topped it up today( rad) and it since has puked a good amount of antifreeze ( time to install an overflow bottle) So...still not sure what to do with respect to this problem. Still undecided if I am going to pull the heads to check the headgaskets...but I think the intake started leaking oil today during my ride....so I may just go in all the way if that needs doing.
Now on to the knocking engine noise...Thought it may have something to do with oil or timing advance. Oil pressure drops off @ idle to almost nil after 160-170 degrees, so I dumped it and changed to 20W50. Better, till it hits 170-190...then same issue... reads 20-40 lbs under load- but drops right off at idle. Added a bottle of Lucas oil stabilizer just for fun... made a differece at the beginning...but then same once warmed up hot again. So nothing good/bad to report there.
Pulled the vacuum line off the dist and plugged it. With no advance, runs a bit rough at idle, but once the weights start to kick in after 2000 rpm, it's ok. Moreover.. the good news was the bad 1700 rpm knock has moved and is mostly gone.
It seemed to moved up to 2500-2700 RPM plus range, but not as bad as it was. Before @ 1700...Used to make the noise bad enough under load, but worse when you backed off the gas. Now with the vacuum line off...it doesn't do it till farther up the range...and then stops when you get off the gas.
I am thinking it's time for a new distributor..something that doesn't pull as much advance with vacuum hooked up...and doesn't advance as much with the weights at full RPM. I have yet to check the curve ( as I need a dark enough place to do it and some help). Will shoot for tomorrow at a buddys garage..and see how much advance comes on ( and when). I am really hoping that after I can nail down those variables, and possibly get a new distributor, this problem will go away.
Still welcoming more suggestions ?
05-25-2005, 02:32 PM
quote:Originally posted by 78bronco
do you have the distrobiter in the timed vacumme port or in the full vacumme port? if its in the full vacumme port you will have full advance all the time insted of it working properly off the timed vacumme port. just a thought I also have a spare distrbtor that you can have let me know
HELL HATH NO FURY LIKE A BIGBLOCK
HELL HATH NO FURY LIKE A BIGBLOCK
05-30-2005, 01:45 PM
Went to Fargo for the weekend to see Gary Allan- feeling refreshed I tried to nip my issue in the bud once again. Here are some results from test suggested by helpful folks.
Did a compression check, results as follows
1&2 are @135
3-8 are @148-150 consistently
Seems a little low on 1&2 for my liking on my "fresh" motor.
I re tried dry on 1& 2 two more times, then wet ( added some oil )
Went up to 160-165. For fun I tried 3-4 wet and they went to 170-175.
I was told once way back in highschool this was a good test to see if your rings are ngf or not...
Plugs look mint..I mean like new. A little carbon on the bottom outside of the plug, the electrode looked new with a hint of tan color to it. So that told me nothing.
Going back to basics I re re timed it, 10 TDC on 1 ( used compression gauge for guaranteed compression stroke, re checked fire order and so on. Took the cap off and looked inside. Found little metal shavings in there...appears to be coming from under the plate ( weight side). Cleaned it out with carb clean, then that non flammable liquid wrench. Wiped her all down and buttoned things up. Fired right up, now had a large lag when you press on the pedal, so much so that if you don't feather it till she hits 2000 rpm..she pops and dies. The more you depress the pedal idle to 2000..the more she bogs. Will re check with a light when I check the curve.
Long story short=Still knocks. With the advance hooked & timed this way it knocks at 2500 now ( instead of 1700) that movement in knock only happened with the advance off before. Haven't tried it unhooked again...curious to see if it moves farther up the range again. Something is still wrong...I guess I am just desperately trying to delay pulling it apart.
Two more tests suggested that I haven't tried. One is the curve check ( how much advance and how fast it comes on)..but I need a buddy for that. Other one is try pulling one plug at a time while its in the "knocking" rpm range..so it would "unload" that cylinder...maybe showing me if one or more cylinders has a rod knock if this is truly a detonation issue.
Any more ideas welcome.
06-06-2005, 08:47 PM
At last drive I had set it to 0 or TDC..with no advance hooked up..and it runs ok...I would 97% knock free..you can hear a tinge at 3000 RPM..but that's it. However..it has no low end, so so mid range( for obvious reasons)...pulls moderately from 2000-4000..stops pulling at 4500. If you keep into it or mash it at 4500..it either starts to bog right down and out to 3000 or just backfires and dies ( I am guessing the secondairies are opening, and with extra fuel and no advance it's just choking it). Still the 4MPG issue running this way, but at least it doesn't knock. Plugs still look like brand new..perfect tan..no deposits, no carbon, nothing odd. No vacuum leaks, no coolant issues ( no oil in coolant, no coolant in the oil, no fuel in the oil)
New friend came by to lend an hand/ear/2nd opinion. We went for a ride, stopped on a country road, and checked the vitals. Advance starts to come on at 2000, full by 3500-4000 I think it was, no change at 4500 for sure. It's pulling 24 degrees ( makes sense as it's a 12L) of strictly mechanical.
Hooked the pod up..it pulls almost 30 on it's own. That would make for way too much advance in the 50-56 degree range..so i'm not overly suprised about it knocking at 1700 rpm with the advance hooked up. To give you an idea of the 1700rpm Rattle..sounds exactly like a 7.3 L Powerstroke...to a T...
Anyways today was explosion day for the distributor. I had been finding metal ( alum flakes) in the dist housing...cleaned it the other day..back again today. But today was impending doom day, distributor let go...advance plate was free to move around, free from the pod, it ripped the wires out of the pickup. I had a few things on me so I patched it enough to idle her home ( I wasn't far)..but I guess I will be getting that new distributor I was going to get anyways. Don't think the knock will be solved by it..but It can't hurt. Besides if I scrap this and start a 460 build..I can use the new distributor anyways.
I had also found what I thought was alum flakes in the oil when I did an oil change a couple weeks ago...now I am finding more in the oil that was coaking around the base of the distributor where it seals in the block..it can only be the failing distributor..or some piston shavings..i'm hoping its all from the distributor...
I'll let you know what happens when I stick a new distributor in it...any suggestions of something good to buy???? Considering some of those Chevy cap in coil HEI distributors...anyone ever run one?
06-07-2005, 11:55 AM
Check your cam timing,could be a 3 position gear set on adv. setting,
until your over this,put a stock dual plane manifold back on for
proper vac. readings,sounds like you have several seperate issues????:(
06-10-2005, 06:22 PM
Well I got a distributor off a buddy, rebuilt it and ran her tonight. It was an 18L * (36 mech degrees) which was a little more then I had before, and I set it at 4 BTDC and ran her with no vac pod ( giving me what should be a perfect 40 degrees advance)... Performs much better ( idle to 5000RPM due to the extra advance)..but still knocks @ 2700+ RPM :(
Unfortunately in addition to that...I Also noted the knock seems to be getting worse( louder)
I think ( as I've known a while now) that I am F#$@$D. Been shopping around for a 429/460 I think this round. All of this has left a bad taste in my mouth and I have a bad feeling about 400's now. Oh I suppose I could take it out and drop it at an engine shop..ask them to figure it out and make it new again...I just don't want this to happen again ( lots of $$$ and way too much time involved. ) So much for my "new engine"
Faced with replacing and grinding internals, as well as a cam that I have no actual specs on and a single plane manifold I should toss...The 460 keeps looking better and better. ( as I will likely be spending a whack of cash replacing most everything again anyways).
Anyone suggest some good 460 build specs..??? Truck is a 3/4 ton 4x4...likely in the 6000 LBS range( I haven't weighed it).
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