3.0 liter valve stem size - Ranger-Forums - The Ultimate Ford Ranger Resource

2.9L & 3.0L V6 Tech General discussion of 2.9L and 3.0L V6 Ford Ranger engines.

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Old 02-15-2016
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Join Date: Feb 2016
Location: Martinez Ca.
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3.0 liter valve stem size

Installed my reconditioned heads on the 91 Ranger 3.0 V6. Now the engine smokes oil upon first startup.
The head guy said that he put new 8 mm stem seals on the valves.
He won't stand behind his work, and told me to basically "Go fly a kite", only he used different words than those.
My question is this: Are there two different sizes of valve stems on the Vulcan V6 based on the year of manufacture? Like maybe I've got heads with smaller 7mm valve stems, or something like that.
Can you tell from the head casting #. I've ordered up a new set of seals from Summit.
The Fel Pro, and the Ford # for the stock seal call for an 8mm, but I really don't want to wind up in the same boat as before.
Anyone got an answer for this shade tree mechanic?
Thank you.
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Old 02-16-2016
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Location: Vancouver, BC
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Yes, in mid-'99 valve size was changed, read here: Ford Ranger II 3.0 liter Engines

You can pull off a valve cover and see what you have, you can tell by the shape of the valve spring.
'91 3.0l heads would have 8mm, but a previous owner could have put on later model heads(or swapped whole engine), and if mechanic didn't know the shape difference and just went on 1991 model year there could have been a goof up.

You can change valve guide seals with heads in place, takes some time(1 cylinder, 2 valves at a time) and a smaller valve spring compressor, but no special knowledge is needed.

Other sources for oil on start up is PCV system

And just a heads up in case whole engine was swapped, '99 and up used longer head bolts, head was the same dimensions, the block was what changed, threads for head bolts were recessed into the block, shorter bolts will reach but won't hold very well

Last edited by RonD; 02-16-2016 at 11:38 AM.
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