Engine/Transmission (1998.5 - 2002) HELP...stock exhaust manifold thread size...

[Patriot Diesel]

OK... lost one of my nuts on the OEM exhaust manifold on my Y2K. No big deal... pulled one of the top bolts out and took it with me to home depot. Turns out that the top bolts are 3/8" nut, coarse thread.



I get home and go to put the nut on the bottom stud... darn it... it won't fit... it will spin maybe a quarter turn before it gets tight... probably cross threading...



Now I am thoroughly confused... are the thread sizes different from each other (bolt vs. stud) or are my tops bolts not OEM?



In any case I need to figure out the thread size...



Can someone please tell me what the thread size is for the stud on the OEM Y2K exhaust manifold?



Thanks!!!

 

[NIsaacs]

Not sure of the size, but they are metric.

 

[Patriot Diesel]

could it possibly be M8?



... trying to research it on the internet...

 

[Joseph Donnelly]

They are all M10 x 1. 5 thread. A 3/8 nut will seem to fit as the diameter of the metric is a hair bigger and the thread pitch just a little off. You need to check the heads of bolts--if they say a metric grade like 8. 8, 9. 8, 10. 9 or 12. 9 you know they aren't std American thread. American bolts usually have the hash marks indicating grade.

 

[Patriot Diesel]

Thanks Joe... now I wonder if I will be able to find them anywhere on a Sunday