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Asking for advice about an 86 silverado suburban timing chain slip.
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Asking for advice about an 86 silverado suburban timing chain slip.
Well, hello Chevy forum , I am new to the forum asking for a little advice, first what happened.
my kid bought an old suburban 15 years ago, that had been driven a lot ,with unknown mileage and I took it out realising it was way overdue for a new timing chain. I stopped to eat ,and the drive thru lane was behind where I parked. Backed up, pulled forward, then backed up , then pulled forward again too quickly , and started across a parking lot slow , it went 50 feet then just shut down. At that point I should have towed it, but thought it was another problem it had.
Tried TO START IT OFF AND ON FOR HOURS in the afternoon, heard some metal banging once , but then realised it was not a wire I had been having trouble with to the distributor, but the timing chain had slipped . Cam got out of where it should have been, and ground down ( truncated) the cam gear a bit as the cam got stuck on something and would not turn clockwise, BUT thank goodness it did not happen when driving , only using the starter.
Had it towed home REALISING it had to be the chain slipped and removed timing cover finding the cam timing mark on that gear was not easy to find, but figured it out as to where the mark was supposed to be from looking at a photo of a stock timing gear. It is the cog next to a small hole in the gear perimiter. The cam gear turned backward ok to move again, so I figured when trying to start it and the chain was slipping on the gear teeth it was off so much it stopped on something and the crank turned the loose chain as it slipped on tbe cam gear and crank gear truncating the cam gear. My cam gear teeth were not nylon ,but aluminum.
Understanding THE Reletive 2 to 1 ratio, I cant feel the compression since one or more valves are out of sync, and likely letting compression out due to the valves .
what advice does anyone have to getting my cam back on where it should be, as I figure if I back the cam up to get the marks to line up to the crank dot tooth, then put on the new chain and gear to see if I get compression in number one.
I know I need to remove the valve cover to watch the valves on number one, to see when both are closed in relation to the rotor. But have not had this problem ever before.
This vehicle had to be advanced a lot to make it pass emissions, and took 7 times to pass due to loose chain and quadrojet carb plugs on underside leaking into intake. I am hoping it is not damaged inside from a valve or hurt a piston, but with all the experience here having seen most any situation, I figure who else to ask, but someone who has likely been through this before. Thanks in advance, as nobody can say if theres damage, but I just need to get it back to find out.
I took some photos, but cant uoload tonight.
Note to myself: Well fella, looks like you're on your own again as usual. Not one suggestion. I suppose I might need to rethink this forum nunsuch. Can't be all that difficult. I'll just wing it. If Those reading this want to help, just send good thoughts I'll get it right, in that way all can help. Many Thanks to those who can take a few seconds to do that for me.
Note to myself: Well fella, looks like you're on your own again as usual. Not one suggestion. I suppose I might need to rethink this forum nunsuch. Can't be all that difficult. I'll just wing it. If Those reading this want to help, just send good thoughts I'll get it right, in that way all can help. Many Thanks to those who can take a few seconds to do that for me.
Chuck the timing chain for a Cloyes. Chuck the Rochester Quadajet for a Holley or Edlebrock carburetor. I'd go with Holley, but that's my preference as someone who has rebuilt well over 100 carbs, and done jetting on lots more. The Cloyes timing chain is the best, bar none.
The carb is not the problem, and I already purchased a Cloyes single keyway timing set ( which I have in hand).Mmy problem is how to get the camshaft and crank timing set back to where it should be. I noticed the chain was slipping and ground the timing gear points down, when trying to start it after the chain slipped, because the cam got stuck on something. ( a valve stem, or ?) I'm thinking I only have a couple choices as to line up the marks, but then need to rotate the engine by hand to see if it is hung up any longer as to my description above of the problem.
An edelbrock would be my choice if I changed carbs,. Hollys are good, IF rebuilt correctly , they have lots of parts you must pay attention to set up correctly. So my problem is just how to get the cam right in relation to the crank. I can't proceed till the weekend , for a couple reasons. From my description, do you have Any advice or questions?
The carb is not the problem, and I already purchased a Cloyes single keyway timing set ( which I have in hand).Mmy problem is how to get the camshaft and crank timing set back to where it should be. I noticed the chain was slipping and ground the timing gear points down, when trying to start it after the chain slipped, because the cam got stuck on something. ( a valve stem, or ?) I'm thinking I only have a couple choices as to line up the marks, but then need to rotate the engine by hand to see if it is hung up any longer as to my description above of the problem.
An edelbrock would be my choice if I changed carbs,. Hollys are good, IF rebuilt correctly , they have lots of parts you must pay attention to set up correctly. So my problem is just how to get the cam right in relation to the crank. I can't proceed till the weekend , for a couple reasons. From my description, do you have Any advice or questions?
IMO, I'd pull the lifters out. Something made the camshaft chain slip. Could be old age, or bad/won lifters, you never know. I'll assuming you have the front end intact on your vehicle intact, but it' be nice to check out the cams and lifters, before you proceed further.
That said, you will need to rotate the crank until Cylinder# 1 is at TDC on the compression stroke and Cylinder #6 is a TDC on the exhaust stroke. You can install the crankshaft and camshaft sprockets and timing chain. The dots on the crank/cam sprockets should match-up _exactly_, and I'd use blue or red Locktite on them. Red can be extremely hard to break loose, so if that's an issue I'd go with the blue.
I know there is a lifter that taps slightly occasionally, but unless something is damaged, I don't want to remove the lifters or cam unless its no option.
I will set TDC, then 6 on the exhaust , which I assume is 12:00 on crank, and 6:00 on the cam with both number one valves closed.
I will then install the chain to see if Ive got pressure on the compression stroke by turning the crank several times to see if It has any hang ups . The kid doesn't drive it much as he is disabled, but it just needs to run.
if it isn't damaged, the car runs great , but if it is damaged, then I think removing the cam and lifters is the next step. It only crapped out because the chain was just stretched from age and sprocket wear. At least thats my feelings. Thanks for answering. , when I find out what's up, I will get back with my findings .
Will do, notice below of some more information I found to add to your advice and my previous statement. My intake is not removed, as I found this other comment to someone else surfing the web, but my valve cover will be off to check the valves being closed. I won't get to it till the weekend due to circumstances, thanks and send good thoughts that all will be well with the job. I need a piston stop first, might just make one. 👍
Todays progress on 86 suburban where timing chain had slipped. Thoughts?
UPDATE: Ok, got to the suburban today, planned to make a piston stop, but didn't. I removed the dist. cap and put the timing cover back on with 2 bolts just to hold it. Turned crank till mark on dampner + cover was on 0, then looked at the rotor position. Rotor was not right. Was NOTon one nor 6, but expected that..Took cover back off, and saw timing mark on crank gear was at 12:00)Number one Piston was at the top, but couldn't get help to see if it was on compression stroke. ( still have to remove old crank gear) put the new cam gear on just for reference. Moved cam gear to 12:00 as crank is ALSO NOW at 12: 00 according to above info I posted in dark screen post.
I Plan to remove the old crank gear then put the chain on the new Dbl Rlr crank gear. Have a lot of prep cleaning to do, but after chain is on, I will then see if I have the compression stroke by turning the crank ,as where I have it set, it should be where it fires on TDC if I'm right.
i did something to my back last week, and couldn't do much with all the pain. Still tried as best I could, but I think I saw some info somewhere where you can loosen your distributor and turn it a little back and forth with a test light on TDC between SP wire and plug and check to see if you get it to light , not touching the starter switch but just turning on the key then turn the distributor but marking it first . Might make a whistle for checking for compression stroke, but does anybody know about the turning the distributor to see if it will light a light or not .
Maybe I'm all wet on that, but feel IF I am NOT on the compression stroke for number one, I think I only have to turn the cam forward moving rotor to 6 and I should be good, but if the crank is on 12:00 AND I move the cam gear to 12:00, seems like that would be right. I did not get the V cover off today.
I did notice the chevy timing chain cover must have a trick to putting it back on bottom end first, but anybody got any trick advice on that?
We cooked a bunch of food for the kid today and took it over.then started checking out the suburban. That's how far I got , but might go back tomorrow due to the holiday. Did notice when I took out his radiator , it was clogged up with leaves and dog hair on the front exterior by 60%. Had to brush it well with a round small stainless wire brush to unclog it. Sure was restricting the air.
Comments or suggestions ?
I know I did it backward , but in turning the chain when hooked up, if the marks dont line up then I can move the cam gear to adjust it to . Feel like I made progress anyway.
October 4th, 2021, 12:41 AM
Asking for advice about an 86 silverado suburban timing chain slip.
