Knock

padgett · May 13, 2013

Turning the individual ingjectors off via ES10 (ECM override) seems the best way. Can you hear it from the driver's seat ? Select ES10 and it will read 0 (all injectors firing). Use UP to increment though 1-6. See page 8D-16 and 8D-17 in the 90 online FSM.

TexasJohn55 · May 13, 2013

John F,,,,WHO'S HOLLERIN'? 2 seater and Ronnie, I have pulled wires many times on these engines, works fine but If I had the diagnostics to do it, I would turn off injector drivers one at a time, much simpler. A piston slap or bearing knock will be alot more pronounced when firing vs normal compression loads only. A piston pin will kind of "double knock". Sometimes it will rattle on decel. TexasJohhn

padgett · May 14, 2013

Removed the discussion of the Honda-style dual ignition. Can start a new thread if desired.

Ronnie · May 14, 2013

Can you say "thread hi-jacked?" Should the last few posts of this conversation be moved to a thread and debate of it's own? So we can get back to Machiner55's "knock' problem?

I think we're all anxious to get back to Machiner55's knock problem. I know I am. He said he didn't have time to work on it right now so we're sort of standing around making small talk until he gets some free time to work on it. There's not much more we can do without him.

Machiner 55 · May 15, 2013

To all who have their panties in a bunch. Un-bunch them. Un-bunch them now! (there's them hyphenated words again) I got mine bunched up enough for all of you plus ten more so... relax.

I just went out and performed the two methods recommended above.

1.) The pull the plug wire method.

2.) The turn off the injector via ES10.

In my case here, they both worked.

Method #1 is not recommended for those that may have a pacemaker installed on their pump. Even using a plug boot puller tool and leather gloves, I'd get zinged if my gloved fingers slid from the insulation on the handles. But for those who want to live life on the edge (like me) that's the way to go.

Method #2 would be the preferred way for those would rather be heavy into bonds instead of the Mr. Toad's Wild Ride Stock Market.

From the comfort of the driver’s seat you can punch up the ES10 override and select (scroll to) which injector you wish to kill.

Using Method #1 then #2, I was able to ascertain that it is definitely Cylinder #2 that is generating the knock. This, at first, surprised me but after thinking about it a bit, made complete sense. Prior to this test, if you were to ask me which cylinder was causing all the racket I would have sworn (and I do!) that it was either #4 or #6. It took two tries with both methods to make me believe it was really #2. This made sense. I'd changed out the PS pump last week because I thought it might be a bad bearing in the pump making the noise. I thought this because when I used the stethoscope, the knock was louder when I touched the reservoir with the probe. Keeping in mind that the pump is mounted right next to #2 well, there you go.

In summation.

1.) We’ve verified that the #2 cylinder is where the knock is coming from.

2.) We now know that the knock goes away when combustion is removed from the cycle.

3.) We know that the knock is absent when starting cold.

4.) We know that as the engine warms the oil pressure starts to drop and then become erratic.

5.) We know that as this happens, the knock becomes evident.

6.) What we don’t know is, is what the root cause of this event is.

So……. what it is?

John F.

Edited May 15, 2013 by Machiner 55 (see edit history)

Ronnie · May 15, 2013

Glad to hear you were able to isolate the cylinder that's knocking. I think you're looking at having to pull the oil pan next.

Here is a photo of the tool I use to handle the spark plug wires. It's a tool designed to pull high voltage fuses. It's about 8-9 inches long and made of some type of non-conducting fiber. Probably Micarta. No gloves needed as long as the tool is clean and dry and you don't get your hand too close to high voltage terminals.

Machiner 55 · May 15, 2013

Ron,

Where's the challenge in that?

Besides, I don't think that when they designed the set I used, that they thought anybody was going to use them on a running engine. Maybe they should have though. There's probably a warning of some type on the packaging they came in regarding using them on a live circuit but, who reads that stuff? :rolleyes:

John F.

TexasJohn55 · May 15, 2013

John, now you are making progress, cake walk from here. You have greatly narrowed what things to look at by pinning down the cyl. So, what you got? piston slap or skirt or bearing clearance issue? Piece of cake!. TexasJohn

TexasJohn55 · May 15, 2013

PS, Don't spend energy trying to troubleshoot the failure until you identify it All the scenarios in your head is a waste of mental resources intil you get there.

Edited May 15, 2013 by TexasJohn55 (see edit history)

2reattas · May 15, 2013

The engine I just tore down was hammering #2 rod bearing, mine had chucked the center 2 cam bearings, it had been sitting a long time, there was enough sludge in it to plug the screen, oil starvation or a failing oil pump seems to be a ause

padgett · May 15, 2013

2Reattas - was that a '90 that dropped the cam bearings ? I have heard of a couple on mine I replaced the engine and was silent when I did but taking out a rod bearing could haave been the next step (I had a max of 19psi at 2000, none at idle, found two cam beaings in pan.

Oil goes from the pump to the cam first, then the mains, nad finally the rods. If you lose pressure, the rods are the first to go.

2reattas · May 15, 2013

Yes it was a 90

Machiner 55 · May 15, 2013

Padgett,

So, you're suggesting that the root cause to this issue is the located in the cam bearings?

John F.

harry yarnell · May 15, 2013

I think the next step is measure the oil pressure. Since it's a '90, what does the IPC gauge show? Should be at 12 o'clock.

Machiner 55 · May 15, 2013

Harry,

Oil Pressure data in post #15.

John F.

2seater · May 15, 2013

On a previously rebuilt (by me) 1989 engine, I noticed the oil pressure dropping also. I found a badly worn front cam bearing due to the new style chain tensioner wear (another story previously posted). That is where the oil first enters the engine from the oil pump. I also found odd rod bearing wear, no real damage, but abnormal for 38k miles. I assumed it was from my turbocharging experiments, but perhaps it was also from an oil leak in the cam area?? Certainly worth looking at if no other cause is found.

padgett · May 16, 2013

Am saying I have heard of a small number (now one more) of '90 "C" 3800s that dropped cam bearings. In my case it was the first time it started after sitting out for a really cold January night in Indiana (now ex-wife was visiting relatives).

Took to local dealer who said the gauge was bad. Drove 1,000 miles home at Interstate speeds running perfectly but showing 19 psi at 70 mph. Found two cam bearings in pan when dropped. I replaced the whole long block.

TexasJohn55 · May 21, 2013

Machiner55, 5 days since you updated us, have you pulled the oil pan and identified that knock yet? TexasJohn

Machiner 55 · May 22, 2013

TJ

See post #29.

John F.

TexasJohn55 · May 22, 2013

Ah! I get it now! Thanks, TexasJohn

Machiner 55 · May 24, 2013

To all,

No time tonight for text. It's late and I'm too tired but I wanted to get the pics posted.

TexasJohn55 · May 26, 2013

John, Thank you for the very good pics. Very sorry for your misfortune. When you get time, post us a quick summary of what you found. I see quite alot but not sure about a couple pics.. TexasJohn

Machiner 55 · May 26, 2013

TJ55,

Since a picture is worth a thousand words and I posted 16 pics, that would be 16,000 words. That's a whole lotta words so, I'll be brief.

The journals are scored, the bearings are to. I'm not going to bother with trying to put new bearings in and hope for the best. Since it's not a daily driver, I don't have to hurry to get it back on the road.

I'll either try finding a low mileage used engine (not likely). Rebuild the 3800 I have on an engine stand in the garage (that one was making one h*ll of a racket when I pulled it). Or, purchase a re-man long block for about 1500 bux and go from there. (preferred method)

I was wanting to take it to the national meet in SoBend this July. That's a month and a half away. Don't think it'll be fixed by then. I wanted to take some time and money to "pretty it up" but the funds will now have to go into the engine. C'est la Vie.

Also, I just loaned my Son a big chunk of change to open a home brew store. You can help by buying your supplies from him.

Don't home brew? Get started! It's fun for the whole family (those over the age of 21 that is)

John F.

Edited May 26, 2013 by Machiner 55 (see edit history)

TexasJohn55 · May 26, 2013

John, I can't tell from the pics, did you have a cam bearing failure? I also could not identify the parts laying in oil pan. Was the suction tube loose in the screen? Did you conclude what caused the failure, there is a lot of recirculation and trash showing in bearings. I am a mechanic by profession just to preface what I am going to say. Those grooves on your crank journals in and of themselves don't concern me. You can polish them with 320 and 400 aluminum oxide roll cloth, it comes in a variety of widths and can be split stripped to any desireable width so you can make a complete wrap on journal. Main concern on rod journals would be miking the diameter, if within wear limits, slight grooving will have no effect on reliability or oil pressure. I cannot see it all as well as you but I would be inclined to replace bearings and run it if the rod bearings miked small enough to cause a clearance knock. Just my opinion and I won't be insulted if you decide otherwise. TJ55

Machiner 55 · May 27, 2013

TJ55,

I appreciate the reply.

1.) ... did you have a cam bearing failure? *** Unless I tear into it further I don't know how else to make that determination.

2.) I also could not identify the parts laying in oil pan.*** No parts in the pan. Just a bunch of powdered copper suspended in the oil. No chunks or chips etc.

3.) Was the suction tube loose in the screen?*** In the picture of the tube assembly, you can see a gap between the screen dish and the tube.

4.) Did you conclude what caused the failure, ... *** No. Just reassembled, put a new oil pan gasket on and filled with oil. Threw some STP for high mileage engines in there too.

For now, I'll just let'r sit.

John F.

zoltanb · May 27, 2013

With cooper sediment it has eaten a bearing somewhere, it is the heart of a bearing. Overhaul or replace. Sorry

Ronnie · May 27, 2013

Don't know the history of this engine but if the engine top end was in good condition... installing a crankshaft kit is a less expensive and easier option. Engine has to come out but heads, pistons etc. don't have to come off unless bearing has spun in a rod. Don't see that in photos.

Machiner 55 · May 27, 2013

Ron,

Only pulled 4 of the 6. None were spun.

John F.

padgett · May 27, 2013

Look carefully at the cam bearings for any that have "walked". Is visible in block above the crank.

TexasJohn55 · May 27, 2013

Re: post 65................Pan is up guys.

Machiner 55 · May 27, 2013

Padgett,

I was unaware that the cam bearings could be seen with the pan off. Too late to look now as the pan has been reinstalled.

As mentioned in previous post, I have to get in, "git'r done & get out of the garage. Wife's car needs it's space and since I do all my own work, I need the garage open for other members of the "herd" should they fall ill.

John F.

padgett · May 27, 2013

Did you determine the source of the knock ? (If a rod bearing whould have been able to feel it move a bit when cap is on).

DAVES89 · May 27, 2013

Wally's in Oshkosh has a '89 "C" motor with just over 107,000 miles on it they want $280.00 plus a core or $100.00 more... It's in the yard due to very slight front end damage. My nephew works there and said it ran great when it came in about 5 months ago.

padgett · May 27, 2013

Considering how bullet proof these are that sounds like a deal, just ask to be very careful when pulling not to break all of the sensors off. Drop this in then take your time with the "numbers match" one. I'd replace all the freeze plugs while out.

I still have the block that dropped the can bearings in the last century. Is there a way to install oversize cam bearings now, wasn't then ?

2reattas · May 27, 2013

The block I just took down they said was out of tolerence and he never heard of oversized cam bearings

DAVES89 · May 28, 2013

I was wrong. I went to car-part and looked it up. It is $165.00 plus $100.00 core.

Machiner 55 · May 28, 2013

Padgett,

I'm working with the assumption is that it's the rod bearings. As for the movement, there was surprisingly little considering the wear. Since I didn't attach an indicator to measure the amount of slop (technical term) all I can tell you is that it was more than the grand or three required for oil clearance.

I looked at a couple of YouTube videos and can say that it wasn't at all like those. In one, the guy was pushing up on the rod cap and it was click-clacking like there was no bearing material left in there at all. Mine wasn't like that.

When I saw the scored crank I just kinda gave up on the idea of making a silk purse of it.

Kind of amazes me though that, that little bit of extra clearance makes such a noise. In any event... If pulling the engine to properly service the crank is what's required, I just would rather just drop another known good used or re-man engine in. That brings me to Daves89's post.

Dave,

You are a long way off up there in Appleton. I flew into Wittman Field for a touch & go on a long cross-country trip in what seems like a lifetime ago so I know where you're at. Kinda. That's a long way to go to pick up an engine. But, thanks for looking.

There are several salvage yards within a 15 - 20 mile radius of Valparaiso. Although, none have a knowledgeable and reputable guy, such as yourself, to check on one for me. I've checked Ebay listings and $300 is about average for a used 3800. That being said, do you or anyone else here know what the latest model year 3800 VIN "C" engine I could use as a replacement?

John F.

Edited May 28, 2013 by Machiner 55 (see edit history)

padgett · May 28, 2013

"C" was 1988-1990, 1991 Buick produced the "L" (Tuned Port Injection) which needed an entirely different ECM program. 90-91 used the same dash so you could update if you get the ECM and a '91 BCM. Not everything got the "E" trans until '92 though so would need a non "E" Prom with a 4T60. Stretching but think the 1991 Bonneville got an "L" engine with a 4T60 trans.

IMNSHO the best "L" is one for a 1992 TranSport - it had no EGR.

ps I just use plastigauge.

pps knock is a function of clearance and oil pressure. If you do not have much psi then a little play can knock. Do agree, I did not see anything really rong, could you catch a fingernail in any of the grooves ?

Edited May 28, 2013 by padgett (see edit history)

wws944 · May 28, 2013

How about a '94-'95 L67?

TexasJohn55 · May 28, 2013

John, I don't mean to beat a dead horse but that crank is not an issue. You could easily polish it up and put in a set of bearings. If nothing else, it would tell you if the knock went away and would still be driveable in the interim while giving you time to build one if desired. You will also have the chance to inspect the cam bearings to see if any spin with the cam while hand turning the engine. TexasJohn

Knock

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