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CumminsApart, Cummins Technician
Category: Heavy Equipment
Satisfied Customers: 89
Experience:  Factory trained Cummins Technician- Automotive, Agriculture, Marine and Power generation
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The head from a Cummins ISX engine..mounted..timing

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Hello, I'm am about to remove the head from a Cummins ISX engine. I've removed all the left and right mounted attachments of course. I'm uncertain about the gear timing. I'm an old dog and have done Cummins and Detroits and other engines in the past I'm use to seeing timing marks on the gear facings. I have inserted the timing pin through the left side of the block and I have the balancer on the insert marking aligned with the timing covers marking. However, I do not want to remove any gears from the cams until I am assured I have the timing on TDC or correctly positioned before I remove the gears. Just to let you know what the heck I'm doing I am replacing the head gasket do to a leak at the rear.   HELP
Hi There,

The cam timing on the ISX is totally different from older cummins. You will need to buy or borrow a timing wedge kit. The correct wedge is then inserted to hold the cam at the correct timing while the gears are set. I can get you the pages from the manual but will be no good unless you can get the wedge Kit.

Another option is to have a cummins dealer set the timing once you have assembled the engine to that stage. You may be able to purchase a good used set on the cheap (if you do let me know, I can always do with these tools too :-) ... ).

If you get the kit let me know and can get you the procedure.

good luck
Customer: replied 8 years ago.

I think I read enough to understand the procedure. First you bar the engine over to the balancer marking of INSERT PIN. Remove the allen plug on the left side of the block. Insert the timing pin into the crank so the PINS GREEN MARKING is about half in and half out. Now the crank is in the initial stage of the timing steps.


After I install the camshafts I install the wedge gauge (in this case #XXXXX on the injector cam and a #6 on the valve cam) this info is found on the valve cover. Ensuring that both wedges are properly seated. Now these engine componets (crankshaft/injector cam and valve cam are in time). Now I install the injector gear and turne gear to the right (facing the front of the engine) to take up any gear lash and tighten. Then I install the valve gear and turn this gear counter clockwise to take up it's gear lash and tighten. Of course I have to torgue to specification and so on. This engine is a 02/2002 model year and is not equipped with a scissor style gear so no spring loaded bolts to deal with. How am I doing? Is there any other tips or things to be cautious of?


This is my ego talking. By my question it may not sound like it but I've done numerous Cummins 855 series engine, old two cycle Detroits 71's and 92's (now I'm showing how old I am) and a few Caterpillars. To date I've have never screwed up an engine job and I do not want to start now. So if you can help me out. Or do you think I'm okay in my procedures.

Hi There,

Yes you have it right ... there is nothing else I can think of that is any different than installing any camshaft.

You have set the valves, injectors and jacobs on an ISX before? It's fairly straight forward except for setting the jacobs where you will need to ensure the rocker shaft is in the correct place so you achieve the set clearance and the running clearance.

Three modifications we have found for the ISX. Increase the breather hose size to 1" by removing the plastic elbow and seal, tap hole with a 3/4 NPT tap and screw in a 3/4 NPT X 1" Hose elbow using pipe sealant on the thread. This reduces cranckcase pressure and hence any oil leaks from weak gaskets and seals. The next problem is the turbo mounting gasket, I have manufactured a new gasket with a center divider to match the turbo flange and manifold flange, this ensures correct heat transfer to stop cracking and burning on both these parts. It is also much thicker to ensure it lasts longer and seal better. This was found to improve the performance of the turbo. Next improvement was to strengthen the top bracket (on the turbo side) between the front cover and the head, this bracket tends to break frequently even after welding.

Hope this helps.
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Customer: replied 8 years ago.


Yes I have adjusted the overhead on the ISX before. Thanks for the other pointers too. We have not had any turbo gasket issues as of ths date. However, we do brake a lot of exhaust manifold bolts at the number three exhaust port. Do you have a fix for this problem? Also do you see a lot of ISX head gasket problems? We have a few that a leaking at the left rear of the head. Oh yeah thanks for the help Pete. Going to hit accept.

Hi there,

Thanks for the accept.

No we have had no problems with the bolts. Just check the alignment of the manifold, bolt it up to the head with no gaskets at about 10 ftlbs and check around with a feeler gauge, especially at No 3. If you find there is a gap, you may need to have the complete manifold re-machined or get another s/h manifold. Do the usual thing and ensure all the threads are good, and always smoother them with excess amounts of a good quality high temp anti-seize. I always give exh manifolds a tap as I tension the bolts up so they seat properly.

We have not had any head gasket problems similar to yours to date, but have had a lot of heads changed due to bad castings and failed injector sleeves. Cummins refuse to accept the core with cracked injector tubes, so I have a few heads lying around and have been trying to work out how we can install new injector tubes.

Good luck