3.2 / 3.5 DOHC Isuzu Timing
We have had a rash of these heads in our shop. It has been amazing to me how many times people call or come back saying we installed the cams wrong. I have researched and asked sevaral other shops including a couple head rebuilders. We all agree that our shop has installed the cams correct.
A few months back we had a 3.5 Isuzu engine in for a rebuild.It was for one of our regular garage customers. The rebuild went well, the engine was returned to the shop. A few days later they call and inform me that they had to send the vehicle to the Isuzu dealer to be timed. It cost them $300.00 and they felt like we should reimburse them. I agreed but told him he should have consulted with me first.
Now just this past week we did a 3.2 Isuzu rebuild. Again it went smooth.
The shop called me and said that the engine would only run on one bank.
They had exhausted all means of checking and wanted me to come by and take a look. I asked him to have the valve covers removed for me.
I spent an hour or so examining the timing, which was correct on the belt, but the actual valve timing was not right with the crankshaft.
Not really using my thinking cap proper, I asked them to remove the engine and return it to our shop so I could find the problem.
The engine arrived the next morning. I put my engine assembly guy on it right away. We removed the cams, pressed off the drive gears, inspected the dowel pins, they were intact. We reinstalled the cams, retimed the engine. As we rotated the engine through its cycles, the vale opening and closing was not right.
The timing marks on the belt and drive gears came right back to the proper place. We did this sevaral more times, consulted a couple diffent timing books. Made a few calls, but it seemed we were doing all we could do. I have just recently bought a book from Motors that covers all timing marks from 1965 to present. I decided to read the words and not just look at the pictures.
It hit me like a ton of bricks. I called my head guy, my block guy and had them to join me and my assembly guy in the engine room.
Its not really complicated, but it is a bit weird.
We all were amazed that the procedure was not listed any where else. I asume that Aldata and maybe Mitchell on Demand has it, but most techs are just like us and only look at the picture.
If any of you have experience a problem with these engines, I'll be glad to share with you how to do it. I am gonna ask the guys at AERA to add the instructions to the tech bulletin for these engines.
Larry Smith Automotive Machine Shop