4.0 OHV Persistent Hard Start. Looking for ideas

[Uncle Gump]

Hard to tell from the picture...

But to me it kinda looks like the exhaust valve seats are all over the place.

I'd have to pop a couple valves out and have a look see...

 

[Kirby N.]

Yes, I think you are correct about the exhaust seats.

I found some pictures of the old ones:

this is the 95tm heads after I pulled them from the junk yard:

this is the lm before they went into my truck after the machine shop finished with them:

now the exhaust valves are way more recessed. Like way more.

sorry I did t get a pic of the top with the springs- I didn’t see anything concerning.

 

[Brain75]

I have to wonder if the changing out of one design head to a different is what caused the valve seats to recess over time, or if it was a lubrication/abuse issue or the machine shop screwed up ... I assume you were pretty decent on keeping oil in it and weren't headed to bandimere every weekend?

If the machine shop was still in business I would ask them what they thought and what their solution would be to keep it from happening again.

 

[Uncle Gump]

Yeah... they all looked sunk. Some worse then others.

I'd bet the intake seats are wonky too.

I'd still likely pop a couple sets of valves out just to reassure my mind that's the seats went goofy.

I also think at that point I would just buy a set of heads.

 

[Kirby N.]

Yeah I was nice to it and kept the oil changed.

They installed new seats, the 93 heads they gave back had seats in them. I wonder if the seats didn't get "seated" and seated themselves over time.

@Uncle Gump if you were buying new heads where would you buy them from?

 

[Uncle Gump]

If i knew where... I would have put that tid bit in my last post.

@gaz @Shran Might know of a supplier

 

[Kirby N.]

@Kirby N.
NOT STOCK COMPRESSION RATIO
• Your rebuild has 1st gen OHV 4.0l small dish pistons
• with 95 heads, which are the fast burn combustion chamber (smaller combustion chamber).

The combination if these two components result in approximately 10.2:1 CR. Depending on how much was milled off those heads you are higher no matter what, just a question of how much was milled. Either way you may need try a tank of premium fuel.

That 93 computer can be either a Sequential Fuel Injection (California with EGR) or MPFI (Federal, non EGR). If it's the EGR PCM, that isn't helping.

Your compression test numbers are wack. How many miles have you put in this rebuild?

Since your fuel pressure is dropping, a prudent move is to install a new gas cap for the filler hose, could be leaking, often overlooked.

@gaz

• my rebuild has OHV 1998-2000 style pistons. Which would be the big dish pistons if I remember correctly.
• It is coupled with the 95 heads, which are the smaller combustion chamber- but the 91-94 style exhaust ports. Which is why I went with them.

So If I understand correctly (feel free to correct me) I am at stock compression ratio- which I believe is about 9.1 to 1.

The heads were decked to take out all warp by .009. So yes a little higher than stock 1998-2000 engines, which I believe is the same as the 91-94 engines, but not a lot.

Is that different then what you thought or am I missing something?

Also, I didn't mention, but in the mix I did add a brand new filler neck because mine was weathered. I used one from a 93 because of the fiberglass bulged fenders- but had to shorten it a little to keep it aligned correctly.

 

[gaz]

@Kirby N.
These Ford OHV 98+ 4.0l were from a Federal 1994 Ranger; received the heads back from the machinist; as pictured, the had been sitting in oil, wrapped in Saranwrap for about a year. I traded for the engine that they I pulled them from, it had been rebuilt @ 220k miles but the original machinist neglected to address the valve train. The valve seats were horribly corroded, especially the exhaust side.

I had my machinist flow bench port/polished them to the intake manifolds with a performance valve job, which included regrinding the valve seats. It required new valve guides, seals and locks as the stock valves were withing tolerance. Thier decks we're milled 0.003"-0.004", just enough to ensure true sealing surfaces. Here is how they looked.

I reread your thread, what is it that you are after ..)

 

[Shran]

I don't know of any suppliers for 95TM heads. I was looking for a set but they are almost impossible to find in rebuilt form and simply not available new.

There are some brand new Ford 93TM heads on eBay but those won't do you any good.

97TM heads would be the easiest to find variant that will work for you (I think) but they have the small exhaust ports.

 

[Kirby N.]

@Kirby N.
These Ford OHV 98+ 4.0l were from a Federal 1994 Ranger; received the heads back from the machinist; as pictured, the had been sitting in oil, wrapped in Saranwrap for about a year. I traded for the engine that they I pulled them from, it had been rebuilt @ 220k miles but the original machinist neglected to address the valve train. The valve seats were horribly corroded, especially the exhaust side.

I had my machinist flow bench port/polished them to the intake manifolds with a performance valve job, which included regrinding the valve seats. It required new valve guides, seals and locks as the stock valves were withing tolerance. Thier decks we're milled 0.003"-0.004", just enough to ensure true sealing surfaces. Here is how they looked.

I reread your thread, what is it that you are after ..)

@gaz
At one point you said I am certainly not "stock compression". But I reread everything and I am sure I am at stock compression- so I was trying to see if I am missing something or if you were mistaken and you didn't realize that I am running 98-2000 pistons and 95tm heads.

Just a double check. Thanks for the pictures. My exhaust valves have really worn out the seats.

I took the heads to the machine shop that bought out the machine shop that originally milled them today. They said the exhaust valve seats were showing extreme wear. Asked me if I got it hot or "over loaded" it. Both of which were a no. I explained how this was the second round with them and the whole history and that I am running stock compression. They said they would talk to the boss and let me know what they would do. They did a lot of arguing with me that it was common wear for a 4.0. But in 30k miles? And I have not heard of exhaust seats doing this- ever. Especially in the miles. And it was all 6 of them- and the intake seats too. I think they must have messed it up.

 

[Kirby N.]

I don't know of any suppliers for 95TM heads. I was looking for a set but they are almost impossible to find in rebuilt form and simply not available new.

There are some brand new Ford 93TM heads on eBay but those won't do you any good.

97TM heads would be the easiest to find variant that will work for you (I think) but they have the small exhaust ports.

I am finding the same- so I am driving a borrowed car currently. We will see what happens with the machine shop.

 

[Brain75]

I would tend to believe they used the wrong seats (either part number or sintered instead of cast) as longs as the head isn't warped into a pretzel. If the heads are badly warped then I might believe it got hot... but like you said, you drove it, you know what happened to it and it didn't get hot/abused.

At your altitude if you weren't running stock (or lower) compression I would think you would know it in a heartbeat - have to run ultra premium to keep it from knocking and pinging louder than the stereo.

 

[gaz]

@Kirby N.
Upon rereading the entire post and taking into consideration your latest information posted, I misunderstood.

If you have 98-00 pistons, which are big dish with 95 heads which are fast burn small chamber, you are near 9:1. The only bit above is from the 0.009" milled from your heads, resulting in an approximate 9.25:1 C/R.

 

[Shran]

That's ridiculous, there are a lot of 4.0's out there with 2-300k on them that have never been opened up. Maybe it is a common repair at machine shops but they probably only see a tiny percentage of heads that are in use... IE, maybe 1 out of 10,000 heads fails and every failure shows up at the machine shop so they opine that they all are junk.

My brain is with Brain, guessing they used cheap parts that failed quickly.

 

[Brain75]

I was searching my hard drive for something else and I ran across some notes on my '48... I instantly recognized what some of it was...

Western Drivetrain was a positive review (glowing) from a guy on the H.A.M.B. board who had 226 straight 6 work done (old 1950 engine). So while my memory couldn't place it my hard drive could. I ended up not having my '48 226 rebuilt, it ended up being cheapest to get a 1949 engine from a guy who rebuilt it then pulled it cause it wasn't hot enough for him.