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Checking for timing jump

 
Old 06-21-2011, 08:09 PM
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Charley B
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Default Checking for timing jump

Probably a dumb question, but if I'm just checking to make sure timing hasn't jumped, is it safe to check just the passenger side or do I really need to pull the other cover too?
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Old 06-21-2011, 08:16 PM
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I guess it depends on why you are checking. If it were me and there was an intake fart or some similar symptom, both covers would be off to check both sides. If it's just a casual look to see how much the belt might have stretched, the pass side is the place to look.

What are you chasing?
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Old 06-21-2011, 08:22 PM
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It started running very rough at start up, after several starts, trying to clear the rough running, the engine started to make some noise. I may have washed down the cylinders, or something else (exhaust) may have been causing the noise, but I thought I better check the dangerous stuff first. It's the GTS.
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Old 06-21-2011, 09:04 PM
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take a look at your aircleaner tap it out onto a white piece of cardboard examine the debris with a magnifying glass, your looking for rubber bits from the belt.

NOTE You should be able to not remove the covers but put the engine at TDC and use the air vent holes to look at the cam pulleys there is a little ridge in each tube the front of the cam pulley groove should be close to this ridge
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Old 06-21-2011, 09:15 PM
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Originally Posted by Mrmerlin View Post
take a look at your aircleaner tap it out onto a white piece of cardboard examine the debris with a magnifying glass, your looking for rubber bits from the belt.

NOTE You should be able to not remove the covers but put the engine at TDC and use the air vent holes to look at the cam pulleys there is a little ridge in each tube the front of the cam pulley groove should be close to this ridge
Thanks, I'll give that a try next.
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Old 06-23-2011, 10:47 PM
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Well, the only question left is how big is the problem. At TDC the passenger cam groove is centered on the vent hole ridge, while the drivers side groove doesn't appear until the damper has moved about 120 degrees clockwise past TDC. The belt only has about 21000 miles but it is eight years old.

The engine pulls all the way through without coming to a mechanical stop anywhere although with the plugs out there are a few places where it takes a lot more muscle, to turn, than other places.

So how do I determine if I have damaged any valves before replacing the timing belt.
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Old 06-23-2011, 11:28 PM
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Oh Noooooo.
Time to remove the timing belt covers all of them and inspect .
Then put the crank at 45deg BTDC and then remove the belt,
then put the cams at 45 then put on a new belt then do a compression test.

From the info you provided you have bent valves on the driverside , but all the cylinders need to be checked for compression.
Are you sure about the timing of the driver side cam??
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Old 06-24-2011, 01:40 AM
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I'll run through it again, but I'm pretty sure.

With the plugs out, should the engine turn easy all the way through? Or could it be normal to be a tough pull at some spots? There is no sound of metal touching metal.
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Old 06-24-2011, 02:01 AM
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I wouldnt turn the engine any more than is necessary to put the crank at TDC,
the valves if they are that far out of time are already bent
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Old 06-25-2011, 09:32 AM
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Charlie any more info here?????
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Old 06-25-2011, 03:10 PM
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I know at the very least I need a timing belt so I'm tearing it down today. I should have status and pictures this evening.
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Old 06-25-2011, 04:22 PM
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Damm.......serious bummer...... About the only "good" news I can say is only 1 bank "skipped".....much better than jumping both banks!!!!

The good news is Sean has about 4 "parts" engines lying around......I'm sure he would give you a deal on a new head/valves
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Old 06-25-2011, 05:10 PM
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Thanx Brian, I hope I haven't ventilated a piston.
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Old 06-25-2011, 06:10 PM
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Charley--

After you have the new belt fitted, you can do an 'acoustic leakdown test' to see if valves are bent. You already have the plugs out so you are part of the way there. You'll want to test each cylinder individually with a little compressed air through the plug holes. I have a compression gauge that has a quick-connect on the hose, and I plug that into a small regulator to do the air test. Or buy a leakdown test set... Put the engine at TDC on #1 cylinder and put air in the cylinder at low pressure. If you hear air hissing through the intake or exhaust, you'll know the valve(s) are bent. Move the crank 45║ for each cylinder in the firing order and repeat the test.

I like this method vs a compression test because it's done without spinning the engine except carefully by hand.

H-F has a cheap leakdown tester. Local parts places like Advance Auto probably have the compression gauge kit to loan (free rental) if you don't have one, so you vcan use their hose and fittings to puff air in. Keep in mind that a lot of air pressure will spin the motor if it's very far from TDC on the cylinder you are testing, so go easy at the valve/regulator as you test/listen.

----

The changes in 'drag' on the crank as you rotate it can be due to differing friction on the various cylinders. The cams seem to have places where you fight some springs as you turn it, then others help a little. Bent valves won't make enough difference in the crank feel for you to notice as you turn it.

We are all praying for you!
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Old 06-25-2011, 06:47 PM
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Originally Posted by dr bob View Post
Charley-- you can do an 'acoustic leakdown test' to see if valves are bent. ----
Thanks Doc. It's been 30 years since I've done a leakdown test. I have a quick disconnect on my compression gage but it doesn't seem to fit any of my receivers. I'll stop by OSH and pick one up.
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