Mazda MX-6 Forum banner

2.5L Camshaft alignment

10K views 4 replies 3 participants last post by  Consequence 
#1 ·
I've re-installed the camshafts in my 93' 2.5L V6 & the rear bank lobe profiles (exhaust cam) are not in the same position as the front bank. (by quite a bit) I used the stamped "dot" on the cam gears just like the front. Seems the lobe position profiles should look identical (front & rear head) when I set them up this way.... Somthing stupid I've done? Any one have a guess?
Also seeking a OBD1 datalogging solution for this car.
Thanks:confused:
 
#3 ·
Here the haines manual complete removal and installation procedure for the cams, if you need diagrams ill do my best to provide em.

Removal:

1. Remove the valve covers, timing belt and camshaft sprockets. If removing the camshafts from the
front bank, remove the distributor om 1997 or earlier models. If removing the camshafts on the
rear bank, remove the intake manifold.

2. The camshafts must be removed carefully. If the bearing caps are loosened out of sequence, valve spring pressure could cause the camshaft journals to cock in their saddles in the head, causing damage.
To provide even valve spring pressure on the camshaft as its removed, align the camshaft dowel pins (I dont have a diagram).

Align the camshaft dowel pins with the mark on the end cap and
the TDC mark. (I'll look for a diagram)

3. Loosen the bolts on the end caps in 1/4 turn increments until they can be removed, starting with the outside two bolts and then inside two bolts.

Loosening end cap bolts:

Cam sprockets .......1
are on this side ......4
...............................B (There is an extra bolt on the rear cylinder head only I labeled as "B", it should
...................................be loosened LAST!)
...........................3
...........................2

5. Loosen the camshaft bearing cap bolts in 1/4 turn increments until they can be removed by hand.

Loosening (must be done in this order, this "diagram" would be if you were looking down at the cams)
This is for the front cylinder head.


Timing belt...............3...11...15...7......Driver's side
end of engine...........1....9....13...5......of the car
..........................The cam is in here
.............................2...10...14....6
.............................4...12...16....8


Loosening, this is for the rear cylinder head

Timing belt.....................8....16....12.....4.........Driver's side
end of the engine............6....14....10.....2.........of the car
...................................The cam is in here
...................................5....13.....9......1
...................................7....15....11.....3

6. Remove the camshaft bearing caps and gently lift out the camshafts, be sure to keep them level
as they are lifted out.

7. Repeat the same steps for the other cylinder head. (Follow the diagram for the rear cylinder head loosening sequence.)

8. Store the bearing caps in the correct order, the caps on the front cylinder head are marked with letters, while the rear are marked with numbers. If necessary remove the lifters with a magnetic tool. Be sure to store them separately so they can be installed in their original locations. On 1997 and earlier models, store the hydraulic lifters upside down in clean engine oil, in a plastic or metal pan.

Installation:

(I skipped the inspection part, refers to another section, if you want it just PM me)

10. Apply Moly-based engine assembly lube to the lifters, then install them in their original locations in the cylinder heads.

11. Apply Moly-based engine assembly lube to the camshaft lobes, bearing journals and gear thrust faces.

12. Set each camshaft in its saddles on the cylinder head, meshing their gears so that the timing marks on the back of each gear are aligned when the camshafts are installed (marks are yellow dots).

13. Apply a thin coat of RTV sealant to the outer edges of the front (larger, thrust caps) bearing cap cylinder head mating surfaces without getting any sealant on the camshafts.

14. Align the dowel pins of the drive camshafts and set the camshaft thrust plates (the one piece cap that mounts just behind the camshaft gears) in place, tightening the bolts only until the cap is fully seated.

15. Install the remaining bearing caps in order.

Tightening sequence, front cylinder head.

Timing belt................15....7....3....11
end of engine ...........13....5....1.....9
..............................The Cam is here
..............................14....6....2....10
..............................16....8....4....12


Tightening sequence, rear cylinder head.

Timing belt................12...4....8....16
end of engine............10...2....6....14

...............................9....1....5.....13
..............................11...3....7.....15

16. Tighten the bearing cap bolts in 1/4 turn incerments in 5 or 6 steps to torque (98-123 in-lbs)

17. Apply a light coat of clean engine oil to the lip of the new camshaft oil seal. Positiob the seal over the camshaft and lightly drive the seal in with a seal driver, deep socket or short length piece of pipe sized to fit the camshaft oil seal. Seat the seal with the edge of the seal protruding approx 0.020 inch.

18. Install the cap plug, coated with RTV sealant, at the front of each driven camshaft. Drive the plug in
with a soft-faced hammer until flush.

19. The remainder of the installation is the reversal of the disassembly sequence.

20. Run the engine and check for proper operation.

There ya go, the write-up minus all the diagrams
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top