engine knock
Printed From: West Coast Fieros
Category: General Fiero Chat
Forum Name: General Talk about Fieros
Forum Description: Just want to chat about fieros? here's the place to make that happen.
URL: http://www.westcoastfieros.com/forum/forum_posts.asp?TID=1642
Printed Date: 23 April 2025 at 2:20am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com
Topic: engine knock
Posted By: rumonk
Subject: engine knock
Date Posted: 14 December 2009 at 4:20pm
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my '85 4cyl has a strange knocking noise, it almost sounds as though the valves are hitting the valve cover, but i've pulled it off and there'e no damage. springs, lifters, arms all look good. the sound does disapear randomly, not at any specific rpm or temp and goes away for 15-30 seconds just as random as it starts. the sound is definately at the same rythm as the valve are operating. i have no clue as what it is so i'm hoping that maybe someone may have an idea as to what's causing this. any advice would be greatly appreciated. thanks. also how do i join west coast fiero, i read the forums all the time and you guys are so knowledgable about these cars and know them inside out. i live on the island but would love to support the club anyway i can. |
Replies:
Posted By: Patrick
Date Posted: 14 December 2009 at 5:06pm
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Someone else can chime in with more insight, but it's possibly just a lifter that's borderline. There's no "easy" adjustment for lifters in the duke, but apparently they can be adjusted/quieted by installing shims on top of the rocker balls/pivots. If you wish to know more about that procedure, I'll see if I can track down a recent thread about it at http://www.fiero.nl/cgi-bin/fiero/Ultimate.cgi?action=intro - Pennock's . In regards to joining the club, I don't know if there's a need to do so if you can't make it to the meetings, but Dave (Capt Fiero) would have the definitive word on that.
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Posted By: D_sensitized
Date Posted: 15 December 2009 at 12:09pm
| From what your describing, it almost sounds like the same thing that happened to my engine, but I have the 2.8 V6. I don't know what it is because I was just gonna swap it out anyway so I never worried about it, but I am taking the engine out hopefully this evening so maybe sometime this week I'll tear into it and see if I can find anything. |
Posted By: Capt Fiero
Date Posted: 02 January 2010 at 11:26pm
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Hit up your local tool place and get a wire type stethoscope. Then probe various areas around the motor. Sounds more like you have a main bearing going out. If you can't find it, I would move up a grade in motor oil and monitor it. It will probably cost more to fix then to replace the motor with a good used one. I have heard of a couple duke motors locally being offered up for $200 I can inquire into them if you are interested.
Now as for the club and joining it. The club does have to pay for the domain and server costs, so anyone that can afford to toss a few bucks to the club it is greatly appreciated. We can then send you the club sign up package, which includes the decal, discount cards and information regarding drives and events. ------------- Capt Fiero 88 Fiero GT 5spd V6 Eight Fifty Seven GT V8 5spd. |
Posted By: rumonk
Date Posted: 03 January 2010 at 11:56am
| after a little discussion with some local mechanics, i've been told to check out the lifters since it was a ticking not a banging coming from the valve area. this past weekend i did remove all the lifters and found that two of them had the oil hole pointed towards the back of the engine as opposed the front. i decided to replace all eight lifters at the same time. all the pushrods seemed straight when i checked them and don't seem damaged in any way, same ass the springs and rockers. i got the engine back together again but wasn't able get it started after (wiring issue) and i ran out of day light. i'm hoping to head back up there this weekend to get it going and see what happens. does anyone know if having the oil hole pointing the wrong way would make it noisy. also where can i send some money into help the club. your guys advice has been awesome and i'd like to help out the club in anyway i can. thanks |
Posted By: Dr.Fiero
Date Posted: 03 January 2010 at 1:07pm
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AFAIK, the 85 was a non-roller lifter, correct? In that case... the lifters actually rotate in use. So - those two were 'backwards' at that moment, but if you ran the engine another 10 seconds, they would have turned, and 1-8 others could be 'right' or 'wrong'. In other words... it doesn't matter. |
Posted By: rumonk
Date Posted: 03 January 2010 at 6:30pm
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actually they are hydraulic roller lifters, they have a a "holder" that keeps the lifters from turning. |
Posted By: Dr.Fiero
Date Posted: 03 January 2010 at 7:20pm
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Dave and I were debating this this morning.... thinking it MIGHT have been a mid-year change thing (like the rounded vs ribbed molding for '86). Regardless - you have what you have. And no, it doesn't matter which way they go, as the oil feed is a ring around the lifter. I have hyd-rollers in my 350 and just replaced them. Nasty expensive in comparison to regular ones, aren't they?!? |
Posted By: rumonk
Date Posted: 03 January 2010 at 8:18pm
| they aren't cheap that's for sure. if this doesn't cure the problem, i'm thinking of replacing the pushrods and rocker arms. i'm positive it's something in the valve train like i mentioned a few times, it's a ticking sound at the exact time the valves are operating. first i've got to figure out the electrical issue to get it running. |
Posted By: rumonk
Date Posted: 09 January 2010 at 7:19pm
| got the engine going, ended up being one of the wires that run from the distributor to the coil somehow broke off. unfortunately the knock is still there. i removed the head to do a full inspection and found that indeed one of the piston rods has blown a bearing. i'm hoping to head up and get the bearings replaced next weekend and maybe do a ring job at the same time. i've never done one of these jobs and i'm curious if i should expect there to be damage to my crankshaft. is there also more of a chance that my piston pin will be damaged as well? |
Posted By: Dr.Fiero
Date Posted: 09 January 2010 at 10:00pm
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Almost for sure you'll need to have the crank turned. Don't bother buying bearings until you've had the crank machined (you'll need to know what it turned down to). If you're REALLY lucky, you might just get away with a crank polishing. In that case, you'll just have to have them still tell you the journal diameters, and see if you still fall within clearance specs. Remember to clean all the oil passages, since that beat up bearing went somewhere.... yup... all through your engine. :) |
Posted By: rumonk
Date Posted: 09 January 2010 at 10:41pm
| thanks i didn't even think about that, man this repair is starting to ba big and expensive pain in the butt! i know i just should have done an engine swap right off the bat, but i decided i wanted to have a long term project and slowly return this car to it's original condition. i'm not really worried about overall hp, i've just always wanted a nice fiero. i've already dumped a bunch of coin into it by doing the lifters and such so i guess i might as well keep going. anyone know what the approximate cost is to turn a crank? same goes for the bearings. |
Posted By: Dr.Fiero
Date Posted: 10 January 2010 at 6:08am
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Been too long to say how much a polish or grind is anymore. But I'd guess around $30 or $100. Bearings are all over the board, but you're around $60 for rods, and $110 for mains. If you get the block hot tanked, you also have to get new frost plugs, and cam bearings as well (~$50 plus install). Complete gasket set is about $130. If you've got the pistons out, you'll probably want to re-ring it. Overbore is optional unless your holes are worn out. Now you're into pistons, rings, getting them hung, plus the bore & hone. I won't even price all that. Suffice to say you've now far exceeded buying one of Daves engines and swapped it to a V6. |
Posted By: rumonk
Date Posted: 10 January 2010 at 10:45am
| in other words, not cheap. ah well, i wanted a project. i was thinking of doing the rings anyways since i had it all apart. i also noticed that each of the pistons have 2 notches on the edge of them facing the front. it almost looks as though they have chipped but there is absolutely no evidence of any damage to the cylinder walls or valves. are these notches supposed to be there or might it be evidence of a previous issue? |
Posted By: Dr.Fiero
Date Posted: 10 January 2010 at 12:19pm
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Sorry - ya got me there. I haven't done a duke in like 7 years. You'd have to find someone that's done it recently... maybe has close up pictures... But if they're on ALL 4, that's rather a coincidence if they all look the same! |
Posted By: rumonk
Date Posted: 10 January 2010 at 1:17pm
| actually they're all diffrent, but are all in the same location. i'll try to get some pics from it next weekend when i head back up. i have also heard people say that in order to flush/fill my coolant that there is a certain way to do it since the rad is in the front. is there any truth to this or is it like any other car? also i keep hearing that i should replace my head bolts because they stretch when torqued down is this true? |
Posted By: Dr.Fiero
Date Posted: 10 January 2010 at 1:25pm
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Coolant: Yes. Special procedure req'd so you don't get an air lock. Bolts: Yes. It's called torque to yield (they stretch). If you just replaced them yourself, you can usually get away with a second round of stretch (it's not "right" but I've done it). If you yourself didn't just do them though... replace them (they CAN snap!). |
Posted By: rumonk
Date Posted: 10 January 2010 at 1:34pm
| i'll be safe and replace them, is there a website that can give me proper instructions to do the coolant? once again thanks for all the help/advice you guys are life savers. |
Posted By: Dawg
Date Posted: 10 January 2010 at 3:16pm
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I just had a Duke apart and yes, there are small machined "notches" in the pistons. All normal, not to worry. DG ------------- You dream it up....I'll make it |
Posted By: Capt Fiero
Date Posted: 10 January 2010 at 10:13pm
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Just a quick short reply on the coolant, the quick and dirty answer is, remove both front and rear coolant caps, start filling at the back have a helper install the front cap as soon as it starts to overflow, then continue filling at the rear until full. Its good to fill it up, run it for 30 seconds and repeat, however in a pinch, I have just done a fill and put the cap on and drove off. The main thing is having the front cap off during the initial fill. ------------- Capt Fiero 88 Fiero GT 5spd V6 Eight Fifty Seven GT V8 5spd. |
Posted By: rumonk
Date Posted: 16 January 2010 at 9:13pm
| well after pricing everything out i've decided it easier and cheaper to just do a swap. i picked up a '84 complete car w/a rebuilt duke. i dropped the engine in mine this afternoon only took me about 5hrs by myself to do, the more i work on this car the more i love it. i may be crazy but in 15+ years of working on my own car and this one is probably the easiest to work on. anyway i'm curious if i need to swap computers from my parts car to work in my '85 or are they identical? is there anything else that needs to be swaped over? i'm doing a straight old craddle out, put new one in. |
Posted By: Dr.Fiero
Date Posted: 16 January 2010 at 9:36pm
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You need to move the entire harness onto the 84 engine.
Nothing on the 84 is the same as the 85. |
Posted By: rumonk
Date Posted: 16 January 2010 at 10:04pm
| can't i just use the existing 84 harness and ecm and put it into the 85? |
Posted By: Romeo
Date Posted: 16 January 2010 at 10:42pm
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' http://www.merriam-webster.com/dictionary/nothing - Nothing on the 84 is the same as the 85.' <- (now with hyperlink!) I'm not too knowledgable in the area, but that statement didn't sound good for your odds, bud. |
Posted By: Dr.Fiero
Date Posted: 17 January 2010 at 9:56am
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Strip your 'new' engine clean. Move what you KNOW is new (or at least better) from the 85 engine onto the 84. Bulk of (if not all) the sensors should be the same. Though they MIGHT not be in the same position (might have to relocate a bracket, etc). Even the throttle cable (etc) MIGHT NOT be the same. Sorry I can't be more specific. I've only ever had ONE '84 brought here over the last almost 10 years! And it was a hacked up monstrosity, so it wouldn't be a good frame of reference. (oh, it smelled awful too!  ) |
Posted By: Capt Fiero
Date Posted: 17 January 2010 at 10:16am
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THe Coil and dist shaft I belive are also diffrent. So you may have to re and re the dist shaft. The reason everyone is telling you to swap, is the 84 ECM won't plug into the 85 Harness at the cabin and if for some odd reason you did get the ECM to plug in, none of the other connectors would work right. Even the lighting and wiring to the fuse block is diffrent on 84-85 cars. ------------- Capt Fiero 88 Fiero GT 5spd V6 Eight Fifty Seven GT V8 5spd. |
Posted By: Patrick
Date Posted: 17 January 2010 at 10:17am
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John/Dave, I know there's quite a difference between the 87/88 dukes and the 84/85/86 models, but it surprises me to hear that there's really that big of a difference between an '84 and an '85 in regards to swapping engines. I'm not saying there is or isn't a difference, I'm just saying I would've thought the swap would be rather straight-forward.
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Posted By: Dr.Fiero
Date Posted: 17 January 2010 at 10:24am
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Pat: you've got BOTH years sitting there. Go pop the hood on both. Just look at the bulkhead passthrough for the engine wiring harness ALONE is, and you'll see how totally different they are. |
Posted By: Patrick
Date Posted: 17 January 2010 at 10:37am
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No, I don't have an '85. I have an 87 and two 84 dukes (and two 86 GTs). Yes, way too many of these silly plastic cars... I'm not suggesting that the way the wiring harness connects at the firewall/ECM isn't different, but aren't the 84/85/86 engines basically the same in regards to the engines themselves being connected to the harnesses (as well as to the throttle cable, etc)?
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Dr.Fiero wrote:
Posted By: Patrick
Date Posted: 17 January 2010 at 10:47am
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John, I'm just afraid that Rumonk is going to read that and jump off a bridge! If he simply uses all the wiring harnesses from his original '85 Fiero, and nothing from the '84 engine/donor car, he should be good to go. No?
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Posted By: Dr.Fiero
Date Posted: 17 January 2010 at 11:17am
Correct. Which is what I said in the first place. Then he asked if could not use the 84 harness, to which I said.... nothing ON the 84 is the same. |
Posted By: Patrick
Date Posted: 17 January 2010 at 12:10pm
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Fine fine, it just sounded rather ominous the first time around. . . . . Will someone please pull Rumonk down from that bridge railing!
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Posted By: Romeo
Date Posted: 17 January 2010 at 2:30pm
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lol "The wiring, it's just too much man!" "Sir, please let other children on the playground bridge." ------------- Never shift into reverse without a back-up plan. |