Finding TDC the easy way.

[Greg Schreiber]

Just replaced the injection pump on my 1973 AMG LDT 465. The TM's all say to remove valve covers and check the rocker arms. Having spent almost 30 years in heavy truck maintenance. I am not one to trust overhead settings that I did not set myself. I took all 6 of my injectors out due to loose hold downs. So I could inspect and change seals and hardware. I barred my engine over from the front at the crank snout. What I used was harbor freight's cheap compression tester kit I had purchased years ago. Turns out the straight rubber tipped adapter is almost a perfect fit. I used 3 wraps of black elections tape.
Knowing two strokes occur with every revolution of the balancer. I was able to find TDC very easily. Of course the pressure registers very low as it's not perfect. But you can feel it catch on compression and the gauge registered 2-5 pounds. I'm sure a second set of hands will help pushing it in.

 

[cattlerepairman]

This is interesting. As I have learned, the fast way to find correct TDC on the multifuel is to take off the oil filler cap and when the crank pulley is on the TDC mark the # 2 exhaust will be open. When you look down the oil filler opening it will be the valve just to the front of the cap hole and you can see/feel it is down.
Are you feeling safer using the compression method to make sure? Or is it in cases when you suspect the engine might be out of time?

 

[davidb56]

Whats a "overhead setting"? do you mean valve position? If you cant trust the valve position in relation to the TDC on the balancer, the engine likely wouldn't run. Not many people would pull a injector (or 6) to find TDC.

 

[Crf450x]

FYI, if you want to find when cyl 1 is at tdc on compression stroke just watch cyl 6. When the exhaust valve is almost closed and the intake valve is just starting to open (valve overlap), #1 is at the top. This applies to any in line 6 engine.

 

[davidb56]

c

FYI, if you want to find when cyl 1 is at tdc on compression stroke just watch cyl 6. When the exhaust valve is almost closed and the intake valve is just starting to open (valve overlap), #1 is at the top. This applies to any in line 6 engine.

correct...and you only need to turn the crank /balancer twice to adjust all the valves. Maybe the TM might even state that.

 

[Floridianson]

This is interesting. As I have learned, the fast way to find correct TDC on the multifuel is to take off the oil filler cap and when the crank pulley is on the TDC mark the # 2 exhaust will be open. When you look down the oil filler opening it will be the valve just to the front of the cap hole and you can see/feel it is down.
Are you feeling safer using the compression method to make sure? Or is it in cases when you suspect the engine might be out of time?

Yep it was Gimpyrob aka Chris that thought me that easy trick. No having to remove the valve cover on a known running multifuel engine.

 

[Greg Schreiber]

This is interesting. As I have learned, the fast way to find correct TDC on the multifuel is to take off the oil filler cap and when the crank pulley is on the TDC mark the # 2 exhaust will be open. When you look down the oil filler opening it will be the valve just to the front of the cap hole and you can see/feel it is down.
Are you feeling safer using the compression method to make sure? Or is it in cases when you suspect the engine might be out of time?

Yes just feeling safer to me to find it this way. The only reason I pulled all injectors was because several hold downs were loose. Figured while I was doing it may as well do it right. Replaced all of the bolts and lock washers on the injectors. As well as the silicone and copper seals. Along with inspecting injectors, their bores and seats and torqued them to TM spec. So along with new pump I know everything is right and the way it is supposed to be. I will try the way you described the next time. Hopefully there will not be a "next time" on this truck lol.

 

[Greg Schreiber]

This is interesting. As I have learned, the fast way to find correct TDC on the multifuel is to take off the oil filler cap and when the crank pulley is on the TDC mark the # 2 exhaust will be open. When you look down the oil filler opening it will be the valve just to the front of the cap hole and you can see/feel it is down.
Are you feeling safer using the compression method to make sure? Or is it in cases when you suspect the engine might be out of time?

That worked very well this go around. Thanks