Zerocyde

So, 92 cherokee with a 4.0 and auto trans. Engine fully rebuilt about 1000 miles ago, including a new timing chain. After removing and putting the trans back in the jeep WILL NOT start. The ENTIRE ENGINE WIRING HARNESS including ECU and all sensors has been replaced to NO change. In desperation I thought that maybe while cranking on the crank pully trying to line up the torque converter I slipped a tooth on the timing chain.

So I get the cover off, put the engine to TDC right after the compression stroke, and the crank gear dot is pointing where it should, but the cam gear dot is 180 off.

Let's make sure I understand what TDC is real quick...

(as you rotate clockwise...)
1. Spark plug fires.
2. Both valves stay closed while piston travels down in power stroke.
3. Exhaust valve opens while piston travels up in exhaust stroke.
4. Intake valve opens while piston travels down in intake stroke.
5. Both valves stay closed while piston travels up in compression stroke.
6. Spark plug fires.

If you take the timing chain off, rotate the cam shaft, and put the chain back on with both dots pointing at each other, you should be at step 1 in my above list right? With both dots pointing at each other if you turn clockwise you should move to step 2 then 3, etc... right?

Well, when I point the two dots at each other and start rotating the engine clockwise it's actually at step 4!! The intake opens and the piston travels down! What am I doing wrong?

Zerocyde

What I don't get is, how is it possible for the cam gear dot to be pointing at the crank gear dot between the exhaust stroke and the intake stroke?

Zerocyde

repost

Deltatech

check the cam gear it might need the dowel moved 180.
There should be 15 chain lengths between the marks.
TDC happens 2 out of the four cycles with TDC after exhaust once and again after compression TDC.
your explanation of the 4 stroke is correct,and you come across as a troll...lol

freegdr

It wont be set dots at each other and proceed. When installing dist you set to tdc compression stroke then install dist.

CCKen

The crank moves the pistons on pairs. For example, 1 & 6 together. The timing mark on the crank damper will align with the zero mark on the timing chain cover twice - once at #1 TDC then again at #6 TDC (180* rotation).

Jeep Driver

Line the two marks up.

Index your distributor.

Bugout4x4

I have a curious question concerning this...Since these have a droopy chain configuration should the marks be lined up after they are on the engine or lined up before you put them on the engine? Because if you line them up before you put them on the engine they are no longer lined up because of the droop on the top side pulling them off a bit.

Zerocyde

So that means if my two dots only point at each other after exhaust tdc and not after compression tdc then I need to move my dowel and 180 the cam gear?

*The Dude*

So I think it was running before you removed the trans, and it wasn't after you removed it.


How long did it sit between?


Did you check fuel pressure and spark before going to thinking you jumped time?


Have you already pulled the distributor or is it still in the original position before you started on the path of jumped timing?

*The Dude*

This might help. The marks should be like this at TDC for #1. Then you slide the distributor in.

*The Dude*

Also, take a look at this page. It gives a good explanation and some good pictures.


But if you have the marks lined up at 0* on the main pulley, and the rotor points to #1 like it should, I suspect you might have gotten on the wrong path for diagnostics. But its good to check it all first.


http://tomasz.korwel.net/2006/12/19/...s-40l-engines/

Zerocyde

The tranny was only out for a day. It's got fuel pressure and spark but the injectors aren't pulsing correctly. The noid light shows weird results.

What I don't get is, how is it possible for the cam gear dot to be pointing at the crank gear dot between the exhaust stroke and the intake stroke?

*The Dude*

I have never had to replace the timing chain on a 4.0, but from what I am reading and the image showing how the marks line up when #1 is at TDC, if you are putting the marks pointing together, the cam may be some where between there.


Look at the picture I posted closely. The marks are not pointing together at TDC for #1. So If you then turn the crank to line the marks up together it will move the cam gear. Usually for every 1 turn of the crank the cam moves 1/4. That allows for the 4 strokes. From what I remember. lol


The important think to check is that the #1 is tdc and that the crank pulley is pointing at 0* on the timing mark. If you have the pulley off and the timing cover off, you can check the actual marks.


Do you have the valve cover off still?

CCKen

Forget that image. It's BS.


You need to have #1 at TDC compression and the two timing marks pointing at each other.


Refer to your copy of the Factory Service Manual, section 9.