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Replacing timing chain

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foxtrot.tango

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I own and 1988 3.8L Auto VN. Since i inherited it 6 months ago i noticed a slight rattle coming down from low revs. Today the rattle is now pretty much there the whole time. Not sure if it is there in high revs because the exhaust would drown it out. I've checked the harmonic balancer and everything else on the engine belt and its not coming from there. Asked about 4 -5 mechanics and they reckon its the timing chain. Sounds about right to me so i reckon i may as well change it.

I have the ellery's workshop manual. Has anyone had the experience of changing their timing chain and or tensioner? If so could you give me an idea of what im up for.
 

Murdoch

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foxtrot.tango said:
I own and 1988 3.8L Auto VN. Since i inherited it 6 months ago i noticed a slight rattle coming down from low revs. Today the rattle is now pretty much there the whole time. Not sure if it is there in high revs because the exhaust would drown it out. I've checked the harmonic balancer and everything else on the engine belt and its not coming from there. Asked about 4 -5 mechanics and they reckon its the timing chain. Sounds about right to me so i reckon i may as well change it.

I have the ellery's workshop manual. Has anyone had the experience of changing their timing chain and or tensioner? If so could you give me an idea of what im up for.

Its not that hard if you have the right tools and all th parts. I did it to my VN years ago.
You just have to rip the timing cover off. Its easier if you take out the radiator.
You have to loosen the sump plugs to drop the front of it to get the timing cover off. This is the hardest part because the bolts are in a prick of a position and the steering rack is in the way for some bolts. I had to drop my steering rack:ranting:
But once its off its easy as. Just make sure you get all the old gasket off the timing cover before you put the new gasket on.
Good luck. If you do it yourself, it will probably take all day.
 
F

foxtrot.tango

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Well i have sucessfully changed my timing chain and tensioner, and the engine runs fine (obviously no harsh rattling and maybe a bit more power/torque)except for one thing. There is a very chronic, though not harsh shudder/vibration coming from the engine. It gets worse/better at different RPMs and worse under load. The sound dominates inside the car when it's at its worst though from outside and in the engine bay it doesnt seem too bad.

We followed the W/S manaul most of the way. First took the +ve terminal off the battery. Undoing the bolt to the balancer we got a spanner and with the drive belt on, put an allen key in the power steering pump pulley and held that in place so the balancer wouldn't turn while unscrewing. When pulling the balancer off we first tried to wedge it off with a crowbar until we bent one of the vanes which run between the CAS. Then decided to go buy a puller. Managed to straigten the bent vane as best we could. Uncliped the oil pump electrical connector and uncliped and unbolted the CAS.

Taking the water pump off was very tricky and ended up breaking off the smaller bolts inside the water pump due to corrosion and had to drill them out The metal pipe towards the back had to come out and was a pain in the arse to do so.

With a lot of levering and elbow grease we managed to take the cover off the water pump then the timing chain cover itself. Inside we found the chain very loose and the tensioner flaping about uselessly and broken. The crank was not set up for the 1st cylinder to be TDC so you could not line up the dots.

We took off everything, the chain, gears and the gear which drives the camshaft balancer. From visual inspection there is only one way everything can go back on unless the crank is moved which couldnt be done with out a lot of grunt and grip. With a close inspection we matched up the the new chain/gears with the old ones and (after lubrication with new oil) slid it back on.

The rubber sump gasket was cracked but we managed to put the cover back on (with the new gaskets) without upsetting it though it was tricky. Put the water pump back together and all the attaching hoses and metal pipes. Eveything thing was pretty much put back on in reverse.

Before starting the engine we gave a final once over to make sure everything looked good and filled the coolant system back up. We decided to be safe and unplug the spark plugs from the coil pack and crank it over once to make sure nothing drastic was going to happen when we started it. Everything went fine. Pluged it all back in and turned the ignition on. Everything went accordingly. We didn't rev to 3000rpm the first time just in case something went wrong. the engine stalled when reving it so the second time we reset and reved to 3000rpm for 10secs. The exhaust smelt and coloured the same, everything sounds the way it should and no engine lights where flashing. Took the car for a drive round the block and straight away could tell something was wrong with this vibration/shudder. I can drive the car fine and it still feels like it has the same power band.

What could be wrong? Please everyone brainstorm. I am so happy that we managed to get it all back together and there are no oil leaks except for a little bit off coolant from the rubber hose. I have never felt this vibration before and and its happens with or without the transmission engaged. The closest thing i've felt to this and its rarely happend is starting in the morning and straight away she'll run fast idle but really rough with vibration similar. When it first happend i tried to rev the engine to make it go away but it stalled straight away. The other times i just left it sit for 20secs and its gone.
 
F

foxtrot.tango

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I am also very soon going to flush the oil out with some Black and gold oil to get any crap out and then with a new filter put Penrite back in. As welll flush the coolant system out.
 
F

foxtrot.tango

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From my hoping guess, it's something maybe to do with ignition/sparkplugs, possibly injectors or sensors. Maybe it's the balancer though for that i would have thought it would get continually worse as RPM rises. I've let a mechanic have a quick look and he said the balancer is fine and it could be your ignition.

Worst case maybe the timing chain is out a tiny bit and the engine vibration is caused by the bad timing and the ECM trying to compensate. Also i noted that the camshaft balancer spun fairly freely. If this is stuffed could that cause a vibration as big as what i'm experiencing?
 

VNPOWER

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id say its the chain. could be too tight..

i had to replace my timing cover gasket due to a major oil leak.. bitch of a job isnt it!! lucky enough my chain was in good condition..
 
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foxtrot.tango

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Yeah it did feel pretty tight with the new tensioner, how could that mess things up?
 

FXST01

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Did you align the balance shaft up with the camshaft timing mark?
 

14secvp

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if your a tooth out on the chain it will still run sweet but the balance shaft will be out of sinc with the crank hench the vibration should allways line up timing marks
 
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