390 exhaust leak or stuck lifter?
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Category: The Garage
Forum Name: AMC V8 Engine Repair and Modifications
Forum Description: AMC-made V8 engine mechanical, ignition and fuel from basic repair to high-perf modifications
URL: https://theamcforum.com/forum/forum_posts.asp?TID=90073
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Topic: 390 exhaust leak or stuck lifter?
Posted By: grparen
Subject: 390 exhaust leak or stuck lifter?
Date Posted: Oct/01/2017 at 12:30am
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I just noticed that my 390 engine, which has only about 100 miles on it since a rebuild, has developed a ticking sound at idle. I thought it might be an exhaust leak but the tick goes away when accelerating whereas I heard that with an exhaust leak the ticking gets louder when accelerating. So, it may be a stuck lifter. Any ideas out there? Also, if it is a stuck lifter, is there a way to free it up without tearing into this new motor? ------------- Gary Parente 1969 S/C Rambler B Scheme 1964 American 330 2 Dr Sedan |
Replies:
Posted By: 401MATCOUPE
Date Posted: Oct/01/2017 at 6:02am
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Start with the basics: 1. Exhaust leak would be the first place to start...AMC's are common to have to the rear bolts on either side come loose, even under low mileage. There was a Service bulletin to replace the bolts with special bolts with drilled shanks, the the bolt would expand fast or faster then the head and would not loosen. 2. Did you use manifold gaskets? AMC precision machined the heads and ex manifolds, no gaskets are needed and usually cause leaks but further down the road in mileage then you are. 3. Sticking lifters or "bad" lifter can cause the tapping noise, most commonly I have found it doesn't go away......I have tried Marvel Mystery Oil on some old cars, original engines and had about 50/50 success, however.....never had it work on ticking "new" lifter, I just bit the bullet and pulled the lifters and swapped the lifters....I know you didn't want to hear that. 4. Did you thoroughly clean the block lifter passage ways with the 3/8"pipe plugs removed, I have seen an incredible amount of debris get caught in this area, have the block "cleaned" only for it to break loose and cause damage....clogging the valve train parts. ------------- Ross K. Peterson 68X,GoPac,343,AT,52A(1stCar) 68X,GoPac,390,4sp,52A 69X,GoPac,390,4sp,64A 70X,GoPac,390,4sp,87A,8 70X,GoPac,390,4sp,BBO,8 70 Jav SST,390,AT,BSO 74MatX,401,AT,Prototype 74MatX,401,AT |
Posted By: kenoshakicker
Date Posted: Oct/01/2017 at 6:10am
| My first car, a 1968 American with a 199, had a ticking noise all of the time. Two people told me to put a little ATF in the engine right before it needed an oil change, run it a few days and change the oil. I did this a few times with no results. The last time I put in a half a quart or better, ran it a few days and the ticking stopped. I changed the oil, started it up, it ticked for a few seconds and stopped. The only time it would tick is when it needed an oil change. |
Posted By: Rebel Machine
Date Posted: Oct/01/2017 at 7:38am
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Did you break the cam in properly? Current oils have insufficient levels of zinc and phosphorus which lead to flat tappet cam failures. Flat tappet cams need the right levels of ZDDP to avoid damage to cam lobes & lifter faces. -Steve- |
Posted By: one bad rambler
Date Posted: Oct/01/2017 at 8:18am
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Rounded over lobes don’t tick....Look closely around the ports for soot...and if your running stock manifolds check to make sure your heat riser isn`t rattling -------------  68 AMX 390 4 Speed,68 American,64 American 2 Door Wagon Altered Wheelbase,78 Concord Build 360,727,8.8
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Posted By: Rebel Machine
Date Posted: Oct/01/2017 at 9:00pm
Mine did. Wore a hole in the lifter face. -Steve- |
one bad rambler wrote:Posted By: ramblinrev
Date Posted: Oct/01/2017 at 9:12pm
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Try the exhaust donut. I'll bet that will fix it!
------------- 74 Hornet Hatchback X twins (since 1977) 62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384 70 AMX 360 4-speed (since 1981) |
Posted By: Red20
Date Posted: Oct/01/2017 at 9:18pm
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To add even more to the list of possibilities: I have an Eaton PS pump that sounds a lot like lifter noise at idle... ------------- 1969 Javelin SST "Screamin' Banana" - Totaled Feb 2018 1973 Hornet Sportabout X "yellajack" - 360/727/TracLoc DAILY DRIVER |
Posted By: ccowx
Date Posted: Oct/01/2017 at 10:34pm
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Here is a trick that works some of the time: Remove the valve cover, after warming up the engine. Put blankets or something over the fenders to catch the mess you are about to make. Start the engine with the cover still off. Take the ticking lifter and loosen it until it starts to rattle and squirt oil all over the place. Let it run for a bit, making a mess, then tighten it down until it stops squirting. Shut it down. Tighten it down to stock specs and restart the engine. This will often blow out whatever crud is sticking in the lifter and causing the problem. This is not guaranteed, but I have about 50/50 success. It is free to try and does not hurt anything. Good luck! Chris PS: Don't forget to put the valve cover back on! |
Posted By: Boris Badanov
Date Posted: Oct/02/2017 at 5:16am
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Got headers? ------------- Gremlin Dreams |
Posted By: one bad rambler
Date Posted: Oct/02/2017 at 8:14pm
------------- 68 AMX 390 4 Speed,68 American,64 American 2 Door Wagon Altered Wheelbase,78 Concord Build 360,727,8.8
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Posted By: wantajav
Date Posted: Oct/02/2017 at 8:51pm
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Get one of those automotive stethoscopes from HongKong Freight. Cheap $3.99 and works great to pinpoint your noise. http://www.harborfreight.com/mechanics-stethoscope-69913.html" rel="nofollow - https://www.harborfreight.com/mechanics-stethoscope-69913.html |
Posted By: grparen
Date Posted: Oct/04/2017 at 9:50pm
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No, stock exhaust manifolds. ------------- Gary Parente 1969 S/C Rambler B Scheme 1964 American 330 2 Dr Sedan |
Posted By: grparen
Date Posted: Oct/12/2017 at 12:56pm
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I notice the tick goes away when I let off the gas while driving. Also, I put a stethoscope all along the valve cover while idling and I do not hear the tick even though it is present. Maybe it's the donut! Any other ideas? ------------- Gary Parente 1969 S/C Rambler B Scheme 1964 American 330 2 Dr Sedan |
Posted By: gremlinsteve
Date Posted: Oct/12/2017 at 1:12pm
| It's an exhaust leak if it's doing that |
Posted By: Red20
Date Posted: Oct/12/2017 at 1:26pm
X2, yep. ------------- 1969 Javelin SST "Screamin' Banana" - Totaled Feb 2018 1973 Hornet Sportabout X "yellajack" - 360/727/TracLoc DAILY DRIVER |
Posted By: limachine
Date Posted: Oct/12/2017 at 2:17pm
| If you're running roller tipped rockers with a hydraulic cam, that's your noise. After they break in, they get noisy. With a solid cam you won't notice, but with a hydraulic cam, it sounds like a bad lifter. Comp cams tech will verify that if you call them (just as an example). Drove me nuckin futs. |
Posted By: limachine
Date Posted: Oct/12/2017 at 2:29pm
| To check for exhaust leaks, grab an insulated glove or at least a folded up rag and with the car running, temporarily block off each tailpipe while your buddy listens if the tick gets louder. Don't seal it off completely! Just apply pressure to the tailpipe and let off a few times and listen for a change. If it don't change cold or hot, no leak. |
Posted By: 6PakBee
Date Posted: Oct/12/2017 at 2:54pm
Well, there's an exception to any rule. This was out of a 392 IH that was quite as death when running.  ------------- Roger Gazur 1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
Posted By: Red20
Date Posted: Oct/12/2017 at 4:55pm
That's also an interestIng point. I heard that from someone at a car cruise. Another guy thought my lifters were noisy and a second guy asked if I had roller rockers and a hydraulic cam. Sure enough. I'm used to it and hardly notice anymore. Originally, I was concerned and readjusted preload twice before just setting it while running with a set of valve covers modified to do that. There was a significant difference in clattering lifters and the lighter chatter that's normal with my setup. ------------- 1969 Javelin SST "Screamin' Banana" - Totaled Feb 2018 1973 Hornet Sportabout X "yellajack" - 360/727/TracLoc DAILY DRIVER |
Posted By: limachine
Date Posted: Oct/12/2017 at 6:08pm
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Yeah, the roller tips will quiet down above 1500 rpm or so. I also had a problem with Chinese lifters. I built my engine with an old stock Crane hydraulic cam, so went with their lifters. 3 of them would intermittently clack away until they felt like working again. So I swapped them out for Comp Cams, and had more problems with collapsing. A little research turned up the majority of the good old brands were being made overseas by the same foreign company with crappy materials and incorrect specs. The only American made brands were Jessel and Isky. I swapped in the Iskys and had better results. After all that, I went solid with Edelbrock heads. What a difference! |
Posted By: Boris Badanov
Date Posted: Oct/12/2017 at 7:22pm
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Exhaust. Sounds like you have headers and a leak. ------------- Gremlin Dreams |