Engine cranks but not starting after rebuild

JONATHANMURPHY2003

MEMBER
1975 FORD F-150
4.9L
6 CYL
2WD
MANUAL
150,000 MILES

I have the truck listed above with a L6 4.9 300 engine. I pulled the cylinder head off and cleaned it all out, I put it all back together with new seals and now the engine cranks but won't start. I am getting good fuel pressure and spark. What are some things I should look for if I want it to get started?

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,418 POSTS

Hi,

If you have spark and fuel, it should run. However, low compression can prevent it from starting. Did you remove the valves? Have you set valve lash?

If possible, could you record it cranking and upload it for me to hear? If not, I need you to check the engine compression. Here is a link that explains in general how to do it:

https://www.2carpros.com/articles/how-to-test-engine-compression

Here is a link that covers the most common causes of a crank no start. Take a look through it as well.

https://www.2carpros.com/articles/car-cranks-but-wont-start

If you look at the attachments below, I found directions for adjusting valve lash. The oldest one I could find was for a 1980, but the engine is the same.

I'm attaching those directions because if they aren't properly adjusted, it can cause valves to not fully close. As a result, compression is lost and the vehicle won't start. Also, when you reinstalled the head, did you place the pushrods back in the same positions?

Let me know.

Take care,

Joe

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