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| Idle issues, and stange noises | |
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| Tweet Topic Started: Mar 18 2011, 08:05 PM (1,057 Views) | |
| Drache Rott | Mar 18 2011, 08:05 PM Post #1 |
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Ok First off a simple question. On the left hand side of the intake is a unit labeled gas filter by the vacuum diagram. What is the function of this unit and how does it function? Mine can be blown though and sucked on with out anything stopping it. Sucking on it seems to be slightly harder then blowing on it but that could just be in our heads. Either way is not hard. no restrictions aside from what the nipple is self would cause. Now to my issue. I have some rather odd knocking sounds coming from the motor on startup that seems to go away as the motor speeds up.My Mechanic helping me with this seems to think it is spark knock or pre detonation.We have checks the bottom end and everything is tight and the bearings are ok. We checked the timing and everything lines up on the marks just fine. The motor is showing 830-860 rpms while running but just does not sound right. I have noted that the vacuum hose running between the idle up solenoid and the idle control valve wants to collaspe and trying to play with the idle valve seems to make no difference in the idle. Is there a way to test either of these for failure? This block has been freshly rebuilt less then 500 miles ago. The Head now been replaced by a new rebuild. The motor had to be rebuilt because the oil ring on cylinder 2 collapsed and both the oil ring and the compression ring on #3 went too. the startup noise and other issues were not present before the motor was sent to be rebuilt. the motor did sit for almost a year after the rebuild before trying to put it in. I have put on a fresh water pump, oil pump, replaced all the vacuum lines with silicone lines (old lines were cracking) and replaced all the gaskets. |
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| Bad Bent | Mar 18 2011, 08:33 PM Post #2 |
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Facetious Educated Donkey
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The "gas filter" is for filtering gas vapors. Gas not as in gasoline but as in air. The hose should go to your distributor advance and be hooked up according to the sticker on the hood. Making it a filter to protect the vacuum advance. Click on http://geometroforum.com/topic/3184772/1/ (IAC Problems) and I believe the IAC test would be to see if the engine runs well with it unhooked, no vacuum leaks. If this engine is rebuilt with less than 500 miles then it could be valve tapping. I would be searching for the source of the noise with a mechanic's stethoscope. ![]() Shat kind of spark plugs did you use? . . |
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| Drache Rott | Mar 19 2011, 09:23 AM Post #3 |
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Hmm it does not feel like there is any restriction on this gas filter. Is there supposed to be any sort of media in it to adsorb the vapors? It was making this sound with the head it had just before we put on this new head too. It's a loud badda badda badda like something is hitting somewhere almost. Can a valve tick sound that loud on start up? The valves do sound noisy(but not any noisier then the old head) I will see if maybe I can record start up on my phone so you guys can hear what it is doing. I am seriously considering taking the cam out of the new head and cleaning the lifters as I do not know if the head rebuilder did it or not. I read somewhere on this site how to do it and that it can remove the normal tick tick tick. Spark plugs I put a set of NGK V powers in it. We have been checking for the sound with a stethoscope. Loudest place we hear a sound is on the water pump..but I don't know of a way for this water pump to make that kind of sound. Sorry on my last post I forgot to mention that the old head had to be replaced do to a communication issue causing it to be run low on oil eating the cam and the cam girdles in the head. Checked rods and mains and all that and they are ok. |
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| Drache Rott | Mar 19 2011, 07:01 PM Post #4 |
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This is a 91 metro 4rd with the 3cyl w/auto btw. |
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| Bad Bent | Mar 20 2011, 02:26 PM Post #5 |
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Facetious Educated Donkey
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I have never played with the 'gas filter' on the intake manifold. Video would be great and you'll get other opinions... I do not know sounds which is why I am no good at timing by ear. You could remove the Alternator belt and see if the water pump pulley wobbles or if the pump has any signs of a bad bearing or broken "fins?" that would cause the noise. Click on Rebuild Lifters. Before the lifter rebuild I'd dump the recommended amount of Marvel Mystery Oil in the oil and see if there is any change in a few hundred miles - granted the water pump is not the issue and explodes in that time. Kidding, sorta on the exploding bit.
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| Drache Rott | Mar 26 2011, 09:41 AM Post #6 |
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I took it to another buddy and he seems to think it is rod knock coming from #2. When my Mechanic thats helping me gets over here we will pull the water pump and look at it for grins...if its ok then we are going to pull the motor and take it back to the mechanist that did the bottom end and tell him to check it. I am also going to get a video of its sound starting before we pull it. It might not get pulled today as it might rain. |
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| mcmancuso | Mar 26 2011, 10:45 AM Post #7 |
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Does the knock speed up if you give it some gas (it has to be related to engine speed if its in the engine)? if not it may be the IAC clicking, pull the wire off it and see if it stops the clicking, its under the air filter cover on the right side of the throttle body:
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| Drache Rott | Mar 26 2011, 11:00 AM Post #8 |
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It makes the knock on start up. The knock goes away after about 20-30 seconds. It comes back and gets faster upon stepping on the gas. Just pulled the water pump and there is no visible scrapes, gouges, or broken teeth on either the water pump or the housing it sits in. this is far to loud to be the IAC clicking.I have entertained the idle that the motor is running lean...but I would have thought it would need to get the rpms up higher before it started lean knocking. I suppose it could still be a spark knock if the ignition module or computer is screwy. Where is the computer on this thing and what does it look like? I found a small finned box near the plug you jumper for doing the idle. |
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| mcmancuso | Mar 26 2011, 11:04 AM Post #9 |
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The computer is up above the fuse box under the dash, its horrible to get to I think you can take the gauge cluster out and get to it that way. You may have a lifter that's not pumping up, or is draining out when the car is sitting and needs that start up time to refill. In which case the mechanic didn't do a good job cleaning the lifters out. This is a really important step in a rebuild on this engine since the internal components of the lifters are really tiny and get clogged by junk in the oil. Rod knock is very uncommon in these engines, and if new bearings were put in I'd almost certainly say that's not the case. The rod and/or crank themselves hardly ever get worn enough for the engine to knock with fresh bearings.
Edited by mcmancuso, Mar 26 2011, 11:08 AM.
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| Drache Rott | Mar 26 2011, 08:41 PM Post #10 |
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ok upon pulling out the motor and checking a few thing out I have found a few things. the original scraping sound I was hearing with the car appears to have been a defective water pump lightly scraping the inside of the housing...that sound went away. It would seem it scraped lightly until it cleared enough material away to clear fully. I think I am going to replace the water pump as I do not know what damage it has internally to cause it to act up in the first place. I do know it would not cause the rod knocking sound. The second thing I found and I am not sure what effect it would cause but or hows its doing it is that one of the bolts that held the flex plate to the engine backed out. I can see where it looks like the bolt was hammering on the torque converter some. What I do not get is how it was moving in and out to hit it. all the other bolts were tight and there does not appear to have been any slippage between torque converter and the flex plate. The mark on the tc from the bolt looks like it was hitting it not dragging on it. So now we are going to loctite the bolts in place and put it back in on Monday and see if we still have the noise. What I do not understand is how it is getting the force to make a striking motion. Can 1 bolt loose on the flexplate get enough flex from vibration to get between 1/3 and 3/8s of an inch side to side travel? I could see if it was 2-3 bolts..but it 1 bolt out of 6. |
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| Drache Rott | Apr 1 2011, 11:18 AM Post #11 |
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Update. When trying to remove the bolts to loctite them on the flexplate we found that 2 of the bolts were broke off in the crank which would allow it to flex all over the place. We are still trying to drill out one of the bolts. I am hoping that will be the knocking issue. |
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| Drache Rott | Apr 15 2011, 11:01 AM Post #12 |
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Final Update:(We Hope) It took some work to find bolts to fit the crank that were the right length and hardness and thread pitch. I finally found them at AutoZone. Brand new item for them . Dorman part # 981-521. I do not know if anyone has a useful part number list on the board but this was such a bear to find that it probably should be added if there is one. As of installing the new bolts and red loctite'ing them the sound of a rod knock was gone. The odd scraping sound was still there. Working around with the mechanic stethoscope we kept getting the noise coming off of the starter. Odd we thought. We checked and the shim was in place. We kept starting at it and thinking something just seemed wrong. Well it turns out that one part of the shim has thinned out after all the times the motor had been pulled and put back. We found a washer with the right size hole to fit over the dowl pin and no more scraping noise. I hope this mess helps someone else out. Long Story short. Flexplate to crank bolts backing out can make a sound like a rod knock from banging into the torque converter and the starter shim squishing out somewhere between 1/32 and 1/16 of an inch can cause a hateful scraping sound that does not go away. |
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| bogs | Apr 15 2011, 01:05 PM Post #13 |
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Duct tape heals all wounds
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Nice detective work there, congrats on fixing it
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| Bad Bent | Apr 15 2011, 07:41 PM Post #14 |
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Facetious Educated Donkey
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The hose should go to your distributor advance and be hooked up according to the sticker on the hood. Making it a filter to protect the vacuum advance.


I think you can take the gauge cluster out and get to it that way. You may have a lifter that's not pumping up, or is draining out when the car is sitting and needs that start up time to refill. In which case the mechanic didn't do a good job cleaning the lifters out. This is a really important step in a rebuild on this engine since the internal components of the lifters are really tiny and get clogged by junk in the oil. Rod knock is very uncommon in these engines, and if new bearings were put in I'd almost certainly say that's not the case. The rod and/or crank themselves hardly ever get worn enough for the engine to knock with fresh bearings.
9:39 AM Jul 11