4.0 OHV Persistent Hard Start. Looking for ideas

[Kirby N.]

Never been to that place- sounds really cool though. I might have to check it out!

Wow. $25 is really reasonable. I think I paid more like $65 from the u-pull-and-pay here. Thank you, but I am not looking for cheap or quick. Looking for right and long lasting- never have to mess with it again (or at least for a few hundred thousand miles). This is fresh rebuilt motorcraft bottom end, so I really expect it to go a long time with the correct top end on it.

I am currently driving a borrowed car and I have plenty of time to get it right, so trying to sort right now what the most right solution would be- and definitely not getting in a hurry because when I do that I tend to cut corners. I just got the gaskets for everything over the weekend. I ordered some motorcraft plugs on Saturday.

The ranger is a really capable off-road rig, but I also drive it every day. I drive it on trips across the country and I use it for work. I used to have a daily driver and a built 4 wheel drive explorer sport and I hated not driving my wheeler everyday. So I designed this truck to be everything. It is solid axle, handles awesome on and off-road, has 35"all terrain tires with air lockers. Does excellent in the snow and will tow if I need to. It gets about 17 on the highway and has a/c and cruise control and rear abs. I have been driving it for about 200K miles and I have been through everything on it. I am hoping to go many more. This engine has been a bit of a headache, but with everyones help I am pretty confident I can get it right.

Thank you again for your help and wisdom!

For reference- this is how it looked when I got it- probably 10ish years ago:

This is how it looks now:

 

[Kirby N.]

I learned a few things today and I picked up my heads. The machine shop was calling this a TSB- its not:

I believe it is just a post off of this website.

I have read this over and over. Its a little wordy. 1995-96 Aerostars ran 93tm heads and Deep dish pistons and the early computer calibration. So my setup with 91 computer shouldn't be ran with the 95 style pistons and 95 style head because it will burn down?

I have no idea the source or the "ford engineer". So that doesn't really help. I am told lots of guys are running this setup with no problem- so I don't know why this would hold more weight than that.

So I called every machine shop that was recommended here and on other sites to get some other opinions and most recommendations were either out of business or didn't want to take on the work even in Denver.

I did however take it to another machine shop in my town, and I actually got some answers! The machinist has been working in this industry for 40 years. He looked them over and said it was pretty common. He said sometimes the heat treat on the head doesn't do a good job of hardening and this can happen. When I explained it had new seats put in by another shop he wanted to see the receipt. When I showed him, he immediately said he knew the problem. Apparently SBI used to make a good seat made in USA. A few years ago they started being made in China. And now they suck. The guy said he had a couple do this before switching away from SBI. HE said they dont even machine well.

When I told them they were loud and I took them back and the other shop said they pressure tested fine, but then hand ground the valve seats again- he said why would they need to do that if they pressure tested fine?

So I think this guy knew his stuff and was being straight with me. He said that was why both the intake and exhaust valves took a dump- because the seats are garbage.

He made a phone call and he can get me some repop 95tm heads and put these springs and valves in them.

However, I may have a line on a set of 95TM new old stock heads, so I am going to see how those pan out. They will be here by the end of the week.

 

[Shran]

Noice. I hope one way or another you can put that mess to bed quick.

 

[Brain75]

I do believe that is a post from here on TRS, Edit: It is from enginebuildersmag /edit - I read it as well in the course of learning more and trying to give you the best info I could find. - I believe it was on one of the three "rebuilding a 4.0" tech articles. (I linked one those three a few posts back).

If indeed those are hardened valves you have, I worry about you putting em in another head and having them pound down the seats again... Which was why I threw out I could maybe get you something from the junkyard that was probably factory valves on factory seats... yeah all used, but most likely a compatible setup.

 

[Brain75]

I did a google search for "It will burn the engine down in a few thousand miles" and this is the very first result....

Ford 4.0L V6 Engine

Exploring the Ford 4.0L Engine: Evolution, Components, and Rebuilding Tips for Rangers, Explorers, and Aerostars. Learn more here!

www.enginebuildermag.com

scroll down to "REBUILDING TIPS" - big category heading.

 

[Brain75]

I just re-read that entire thing again and then re-read your first post... I got a question for ya.. where did you get your ECU, what year is that part of the setup?

You said in post #1 you swapped to a junkyard '93 for a short time and then went back, but I don't see where you said what your ECU is now.

....From what that enginebuildermag post says in the "Pistons", "Heads", and "Rebuilding tips" sections, you have to run a 95+ ECU (Ranger/Explorer) or a 97+ ECU (Aerostar), if I understand what they are saying.

 

[Kirby N.]

its a 1991 ECU. The original. Thanks for tracking down that article- that is helpful reading. I am still leaning toward running 95 heads as I dont think the ECU or head/pistons with the ECU was the problem. I think it was the seat. Do you guys think that is nuts?

 

[Brain75]

The author (Doug Anderson) says quite un-clearly not to use 95 heads with any pre 95 "calibration' the calibration is the computer calibration which is in the Engine Control Unit, no?

 

[Brain75]

And I totally agree, the combo of 2000 block and 95 heads is a the best of the most refined/bug fixed versions you can get... I support your goal, just got to do it with all the right parts.. I don't know auto computer hardly at all (even with a degree in programming) so if I am wrong about what the "calibration" is tell me. More than anything I don't want to steer ya wrong or stand by and watch you have a repeat of history...

 

[Kirby N.]

Yeah I agree. Perhaps I am just looking for someone to tell me what I want to hear. @bobbywalter had some cautions that would align with what Doug Anderson wrote. Going to a later electronic efi system wouldn’t be impossible, but it would be quite a bit of work and I am a fan of the earlier electronics with less sensors for simplicity sake. The troubleshooting wasn’t stellar with it- but I was also missing the big glaring issue.

actually the more that I think on it, going to a 95 style electronics would be a ton of work. All the sensors and the wiring harness is completely different with the chassis plug being different, the location of the ecu, the dash, the intake, the exhaust. Everything. I think it would be easier to find some pistons that are for a 93 and swap heads out to earlier versions. Which seems really backwards after all this. I did consider that when I had the 93tm NOS heads in hand, but I couldn’t find any pistons I felt good about that were the correct over bore.

 

[Shran]

I am reading that as "Don't use 95TM heads (or newer ones) on a 95-96 Aerostar" and that it only applies to those two years of Aerostar vans. And that would make sense given that those two years of Aerostar engines would have had the shallow dish pistons, add the fast burn heads and you've got a fairly high compression engine. I think that's where they made a mistake with one of my 4.0's, it was a 94 short block but someone put 98TM heads on it and it would ping under almost any load, even with a full tank of 91 octane and added octane booster.

I guess I'm just not seeing why 95/97TM heads and deep dish pistons wouldn't work for you after reading all that, compression ratio being close to what it was in 1991 would be the main thing in my mind. Obviously I do not build engines for a living so I would sure like to pick Mr. Anderson's brain on that topic - what causes those engines to melt down, is it simply detonation from high compression & low octane, or is it some little detail programmed into the ECM that messes with the timing or fuel or something, IE, a software problem?

 

[SenorNoob]

...I would sure like to pick Mr. Anderson's brain on that topic - what causes those engines to melt down, is it simply detonation from high compression & low octane, or is it some little detail programmed into the ECM that messes with the timing or fuel or something, IE, a software problem?

Same here. I can't see how it would be an issue unless the fueling is different (I have hard the later setup referred to as "lean burn"). Surely it doesn't run that much more timing at startup does it?

On a somewhat related note. I have heard of people running SOHC 4.0s on earlier OHV computers. Supposedly it was fine.

 

[Brain75]

I'm a bigger fan of OBD2 than OBD1 only as far as diagnostics, but in addition to the work of changing it, could you even get a pass at a Colorado emissions station?... They would take one look at it and go it has an OBD2 port it has to pass the full monty instead of the lesser "grandfathered".... That said supposedly they only check if A) the CEL is lit or off but stored in computer, B)there are emissions sensors "not ready" (like you just disconnected the battery to clear a CEL), C) what the actual tailpipe emissions are (hence the run running test on the treadmill) D) headlights and horn.

So as long as you can fool a handheld OBD2 reader into believing all sensors are ready (or all but one), you should pass... but again they might just fail you rather than deal with figuring out your "weird" config.

 

[Brain75]

bobby said something a couple pages back and I couldn't remember exactly what it was but it was computer related so I had to go back and re-read...
(I did the bold font)

the fast burn heads are later and can really be a problem with the early pcms. bank fire or sefi, but bank fire is generally pretty forgiving...

this is why i always suggest keeping known running systems intact on a 4.0. and do not like rebuilding them with cracked heads when i have to find parts...

there are all sorts of changes all through the life cycle. there is a cam biased towards manual and one auto....this combo depending on which piston is in there can lean it out to the point of destruction....

my son melted an engine pretty quickly in the bronco....had i been there to hear what it was doing we would have switched the pcms.....it was an oversight and he finished up putting it together....of course i was not panning on him to do that and beating the fawk out of it out back before i got back to town...

PCM instead of ECU...

 

[bobbywalter]

sweet. i was missing part numbers.

there is...rather you can end up with a bad combo that will really fawk shit up. fast.

several times i have been bit.

that is an updated article from the data i had.


in any case it is simple.

listen carefully when you mix and match. preferably run it on a dyno or where you can concentrate on it when it is under load with low grade fuel and if its good...it is good. if its knocking bad, figure it out.

in this case it is obviously a mechanical issue with the seats.

i was planning at looking to see what we had when i got back home...but with nos units on the way i suspect you will have it going in short order.

i will print that and put it with my notes....great detail.