No compression in #1 cylinder

[mred3]

Hello I have a 2005 Ranger with a 4.0 sohc that all of a sudden started running real rough, got it home and tested it, OBD was giving me a cyl #1 misfire code, after diagnosing, it came out to be no compression whatsoever on #1 after this I decided to hook up the air compressor to the cylinder with both valves closed and air was coming out of intake side, so then I took the intake lifter out and retested with air into cylinder and no air was coming through intake then I checked the lifter it was very hard to compress in fact had to put vise to accomplish this. Bought a couple new lifters and install the intake one thinking this would fix issue for sure, but still no compression from the cylinder, the cam follower looks good, valve spring looks good/intact so what heck could this be never heard of a intake valve being burnt.

Thanks

Ed

 

[RonD]

Well they often make intake valves with metal that can't take extra heat like the exhaust valves get, so intake valves can "tulip" if overheated too much

Tulipped valve doesn't seal when closed, if you remove the rocker it could then close, but with rocker in place it would leak.

Check if valve stem height for that valve is slightly higher than other valve stems with rockers removed.

The cam on drivers side can also "slip" on timing chain which can cause a slightly bent valve on that side, I would expect no seal with rocker in place or off but..........

 

[adsm08]

I agree with Ron. While rare IME tulipped inktae valve seems most likely. A bent valve shouldn't seal at all, lifter or not. Also, if the cam slipped it should have taken out the whole side of the engine, not just cylinder one.

 

[mred3]

Thanks will be doing more diagnostics this weekend will post


Ed

 

[mred3]

Just weird this happen all at once was running perfect before no problems but it does have 178k on engine but always changed oil every 3-4k

 

[RonD]

Well if you tulipped a valve it would "just happen" while you were driving along, it isn't a slow process, may have had some pinging(pre-detonation/knocking) in that one cylinder leading up to it.
Could be an injector was not flowing well and that cylinder got Lean, Lean = VERY hot, and that would cause pinging at first then valve and piston damage.
4.0l SOHC does have a knock sensor since Ford made this engine with a 9.7:1 compression ratio, so prone to pinging/knocking, that sensor should have caused computer to Retarded the spark timing enough for you to feel less power.

Miles wouldn't matter, and that part of valve isn't part of the oil system, if valve is the problem.

 

[mred3]

Ok I can accept that, another question would it be possible to remove head in the vehicle marking the timing chain of course and successfully reinstalling ?
Putting a used or rebuilt head on, I'm thinking if I have to pull engine I'm looking to get a rebuild.


Thanks

Ed

 

[RonD]

You can pull a head(or both) on the 4.0l SOHC with engine in the vehicle.
But it does require complete disassembly of upper engine and front timing cover removal, and if the timing chains and cassettes are original then replacing them at this time would be a very good idea but..............you can't do the rear timing chains with engine in the vehicle so...........up to you.

You still need to re-time the cams and crank even if you don't replace the chains

 

[mred3]

I just was thinking of the passenger side head change only. Timing chain/cassettes look good, If I can get another 100k from it that would be great, but if I have to pull engine I will just put in a rebuilt.

Thanks

Ed