1991 Accord 5sp 215k miles

I am a novice mechanic. I enjoy working on my cars...so I decided to do a tbelt on this car.

All went well, got it all put back together and when I am at cruising speed and give the car gas...I hear a very faint knocking/pinging sound. It sounds like the car is firing too early or maybe too late.

I think that maybe my tbelt is off by a tooth. I have removed the spark plugs, valve cover, motor mount, upper cam cover, and drivers tire.

I put a very long socket extension in cyl 1 to visually see TDC as I was turning the crank clockwise. Once I got to where the extension was not moving up or down when I was turning the crank...I checked the inspection plug near the exhaust shield. I could see the mark on the crank was close to being in align with the "V" indicator inside the inspection hold. I checked the camshaft gear and the stamped "UP" is not in the 12:00 position...it is off some. The two little lines on the sides of the gear where the teeth are located are visible and are roughly in position.

How do I tell when I have everything in sync? It appears as if I can only "eyeball" the camshaft gear if I am attempting to use the 2 lines on the gear that are located near where the tbelt rides on the gear. It is hard to tell when I get TDC because my long extension stops moving for about a quarter of a turn of the crank.

Is it possible to fix my problem without having to take the lower tbelt cover off?
How do I precisely position the camshaft gear in relation to the position of the crank?
I didn't know about the inspection hole when I did the job originally....it seems like I used some kind of marking on the crank gear to align the crank from the bottom side ....(maybe it was a mark on the shaft that I had to see from the top side of the engine looking down at the crankshaft gear)...geesz...how soon I forget.

At this point...I don't know what to do to get my engine back in sync. Any suggestions would be tremendously appreciated.

Thanks
Keith Smith

 

I'm a honda noob too, (just did my first honda TB myself a few weeks back) - so my feedback may not be helpful or welcome.

But you can (in theory) remove a spark plug, and put something like a long, thin rod down into the cylinder, and rotate the crankshaft, to see EXACTLY when the piston hits TDC. When your indicator rod reaches the top. It's either going to be 0 degrees with the cam, or 180 degrees. If your TB was off a notch or two, you should be able to see that. Just make DAMN sure that nothing that goes into the cylinder breaks off or stays down there. A very clean welding-rod, or a long-shank screwdriver or something.

If I recall - there's a notch on the plastic of the TB cover that lines up with a notch on the crankshaft pulley. When you have the pulley and TB cover removed, then I'm pretty sure there's a pair of marks on the wheel and case that also line up.

I thought that the Camshaft was not very easy to line up against the plastic cover. "UP" did not seem "perfectly" straight up, to me. But the result at the end of the job ran nice and smooth. I just lined it up the way it was when I started. Plus, there was a little slop (at the start) because of the belt, and because I had already released the tensioners.

You might review the valve-adjustment procedure in the shop manual, to help understand the order of the intake/outlet valves, (1, 3, 4, 2) and as you rotate the camshaft, you can watch the valve-train operate, and line up the cam wheel precisely at TDC that way.

I know that that plastic cover behind the cam wheel somehow doesn't LOOK straight, but it is. I had to remove mine to extract a broken water-pump stud, and there's no play in re-installation. It has brass bushings embedded in the plastic, so it's pretty firm. I think it's all in the viewing-angle.

 

Did you review Touring Accords writeup in the FAQ on the timing belt replacement?

Did you recheck/adjust the ignition timing after the belt replacement?

 

If I align the mark on the crankshaft (that is visible via the inspection hole beside the exhaust heat shield) with the "V" indicator...can I be 100% certain that the crank is at TDC?

Once I get that...I simply need to get the cam aligned properly and then I am good to go correct?

To align the cam, I need to have the stamped "UP" on a spoke of the gear oriented in the up position and to get the belt on the correct tooth...and I need to do that by aligning the 2 marks on the teeth with the top of the plastic cover that is located behind the camshaft gear? How do I do that without just "eyeballing" it?

 

Okay..that is something that I didn't do....I will go and see how to do that. I will review TouringAccord's writeup and see if it is in there.

 

I didn't see any mention of adjusting the ignition timing when doing a tbelt replacement inside TouringAccord's writeup.

 

The only thing that I didn't understand is the procedure to adjust the tension of the tensioners...(copied from a different thread);
"The correct way to set the timing belt on your engine is as follows:
-loosen the timing belt tensioner bolt (be sure engine is a TDC on cyl #1)
-rotate the crankshaft counterclockwise three teeth on the cam gear
-tighten the tensioner bolt to 33 ft. Lbs."

Not being abrasive here....just wanting to understand...what does TDC have to do with adjusting the tension of the tbelt?

When adjusting the tension of the tbelt...when I put a socket on the crank and note where the cam sprocket is, turn the crank enough for the cam sprocket to move 3 teeth and then tighten the tension nut.....it seems to me that there would be VERY LITTLE tension supplied by the tensioners...

 

I don't think the ignition timing procedure is in there. But it is similar. Warm the engine up, turn it off, jump the blue two wire connector under the dash, or on 90-93 I *think* its by the passenger kick panel. Turn the engine on. And check the timing port with a timing light.

When you rotate the engine if the belts are installed incorrectly, the rotating of the crank will show if there is a misalignment when you bring the crank back to TDC. If the cam is still on the correct marks you are good.
The tensioners are to remove any slop in the belt. They are not designed to keep a heavy pressure on the timing belt. The belt will not slip on the cogs due to the teeth, and the belt will not stretch.
Too tight of a belt and the pulleys will be loud and add load to the engine.
Once the slop is taken out of the belt by rotating, the lock nut will hold the tensioners in place. It is not an active tensioning system. Just set it and forget it.

 

Thanks for the response Mad_Mike.

When attempting to find TDC...I have inserted a very long socket extension into the cylinder. As I rotate the crank, the extension goes up and down. As I am approaching TDC (the extension/piston stops moving) while I continue to rotate the crank.

My question is this....is TDC the point the piston stops moving or when the piston starts moving again or half way in between when it starts and stops moving? The crank and cam both continue to rotate with the piston no longer moving.

KS

 

As the piston reaches TDC, or BDC, the pistons speed slows as it changes direction from Up to Down. This is due to the angular change of the connecting rod as it reciprocates. The connecting rods bottom end is attached to a crank throw on the crank shaft which rotates the bottom end of the connecting rod in a circle.

 

Just to finish off this thread.

The ultimate problem was that the cam was off by 1 tooth.

As far as aligning the cam into the correct tooth...I placed a straight edge along the top of the head so that I could see the marks on the cam gear were lined up better.
NOTE...If you have your car jacked up ... the "UP" stamping on the cam gear will not be oriented in the 12:00 position....rather...somewhere along the 1:30/2:00 position.

As far as TDC, as you approach TDC, the engine will want to rotate past TDC ...so take you time and approach TDC slowly, use a straight edge along the surface of the head, verify the "UP" stamp is actually pointing up and you should be good to go.

As a side note, when I got my engine to TDC, I checked the inspection port of the engine beside the exhaust shield....and the marking " ---l---" was perfectly positioned within the "V" of the indicator inside the inspection port.

Thanks for the help...the car is running correctly as it should.

KS

 

The 'UP' is indeed in the 12 O'Clock position in relation to the crank. But since the engine is rotate towards the firewall the cam sprocket will be clocked to the 1:30 position. There are two notches on the cam sprocket that are to line up with the top of the cylinder head.