4.0 OHV Persistent Hard Start. Looking for ideas

[Kirby N.]

Well I heard back from the machine shop and they are not going to do any sort of warranty for me. They said there is some sort of service bulletin about using later heads with an eatlier Computerand causing a lean condition . However, I don’t think that is exactly what the tsb says. And they didn’t realize that the intake valves are garbage too which isn’t a lean issue.

does anyone know what tsb they are referring to?

 

[Kirby N.]

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.

western drivetrain. I’ll look that up. Thank you!

 

[bobbywalter]

Well I heard back from the machine shop and they are not going to do any sort of warranty for me. They said there is some sort of service bulletin about using later heads with an eatlier Computerand causing a lean condition . However, I don’t think that is exactly what the tsb says. And they didn’t realize that the intake valves are garbage too which isn’t a lean issue.

does anyone know what tsb they are referring to?

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...

 

[bobbywalter]

so i realized i missed several pages...


...not sure what happened from the pics but i sure as hell would like for you to get the heads back and disassemble them yourself and give ss the dimensions of the valves and compare those to stock.

how that engine ran at all is a wonder.

double check the timing gear is correct and not slipped as well.

i will look today and see if we have any 95 or 97 heads....pretty sure those units in the garage are 93. but i did have some 95.

 

[Shran]

Well that sucks.

I am actually seeing three piston variants on RockAuto - 90-94 small dish, 95-00 big dish, and 98-00 slight recess, almost a flat top.

I'm not really sure what to suggest. You could find a different machine shop and have them go through your heads again and hope they use better valve seats (I still think they used cheap parts thus the failure) but that is a tough call, nobody here will know what brand of seats are good and which ones are not, I kind of doubt that most machine shops would know either.

You could put older big chamber heads on it but you lose compression ratio that way with your pistons. Not great

You could use older (90TM or 93TM) heads and older small dish pistons in it, basically back to stock - wondering if this might be the way to go with your ECM, you will have money into heads no matter what route you go

If you fixed what you have now, you could try running a later 93 or 94 ECM or do an OBD2 conversion on it and run '95+ stuff. Late OBD-1 ECM seems like somewhat of a gamble. OBD-2 conversion brings a lot of other things into the mix (cam sensor, EGR, etc.)

But maybe this just happened with shit valve seats and good ones will get you up & running indefinitely.

 

[bobbywalter]

Well that sucks.

I am actually seeing three piston variants on RockAuto - 90-94 small dish, 95-00 big dish, and 98-00 slight recess, almost a flat top.

I'm not really sure what to suggest. You could find a different machine shop and have them go through your heads again and hope they use better valve seats (I still think they used cheap parts thus the failure) but that is a tough call, nobody here will know what brand of seats are good and which ones are not, I kind of doubt that most machine shops would know either.

You could put older big chamber heads on it but you lose compression ratio that way with your pistons. Not great

You could use older (90TM or 93TM) heads and older small dish pistons in it, basically back to stock - wondering if this might be the way to go with your ECM, you will have money into heads no matter what route you go

If you fixed what you have now, you could try running a later 93 or 94 ECM or do an OBD2 conversion on it and run '95+ stuff. Late OBD-1 ECM seems like somewhat of a gamble. OBD-2 conversion brings a lot of other things into the mix (cam sensor, EGR, etc.)

But maybe this just happened with shit valve seats and good ones will get you up & running indefinitely.

yeah.....i learned these things in real time....so it was jumbled....byt the 2000s we were getting a handle on it.

when i was making harnesses for swaps the crazy shit i found in some harnesses made me slow down....then i just stopped fawking with them. there are alot of variances with the 4.0.


3 pistons....the later you need to monitor...rods can have different bob weights...

3 or 4 cams....2 types of crank gears...8 bolt and 6 bolt cranks....

and the heads....

total shit show.

 

[Kirby N.]

Hmm I would like to see the TSB that the machine shop is referring to. I don't think it is a case of computer/ head compatibility. I think it is head and block compatibility. But I could be wrong.

I am leaning toward running these heads again but with a machine shop working on them that doesn't suck. The guy said they used GSI valve seats or something and that if they were a problem they would have had others that were a problem. However, who runs an old truck like this to 30k miles in 2 years? Most people are selling an old truck before 30k, and definitely in 2 years. And it is not like they would tell me if someone else had an issue anyway.

The only two things I can really imagine:

1. They used crap material like someone said. Not hardened or something. Cheap china garbage. They wore out. Perhaps the other stuff they have done has had the same problem- but I am the only guy to actually figure it out?

2. The heads I got had hardened valves for propane. Like these were NOS heads, but for a propane application. The valves were hardened for that, and the seats in the 93tm were hardened too- which would typically be fine. However, the valves were moved to a 95tm head and regular seats were wore out by the hardened valves. I don't think this is a thing because I haven't heard of hardened valves for propane, only seats.

 

[Brain75]

ignoring the words "valve", "seat", etc I searched for 'ford 4.0 OHV TSB' and this is the one and only I got...

https://www.ford-cruising.hu/miscimages/0219.pdf

TL/DR; drop from 5w30 to 5w20 to "increase fuel economy" doesn't say if that is at the cost of engine life or or...

problem is I am not a ford tech/dealer/parts counter guy... just a pure google search. one of the actual ford employees could tell ya... could hit up the local Ford service desk and just ask for the same thing i did 4.0 OHV all TSB

 

[Brain75]

that search also got me a good article here on TRS:

Rebuilding And Improving A Ford 4.0 Engine - The Ranger Station

Original Article Resource: Motor Trend Tick. Tick. Tick. That’s the sound our Ford 4.0-liter, over-head valve (OHV) engine was making in our 1991 Ford Explorer after 250,000 miles. The Ford 4.0L V-6 engines, built in Germany, are found in Ford Explorers and Rangers through … Continued

www.therangerstation.com

 

[Brain75]

this thread (post #5) a guy says the original seats in a 4.0 are cast not sintered

Bad valve seats on my 4.0l

Had to pull heads due to bad exhaust valve seats:bawling: Good news is that I should have heads back from the machine shop Friday. Hopefully it will be done Saturday :icon_thumby:

www.therangerstation.com

sintered is the "everyday" application manufacturers/machine shops will use when they are not building a performance/race rig. (powdered metal compressed into a form instead of cast) When building a performance rig they will use cast seats (they tolerate more abuse)... perhaps your setup (and all 4.0 OHV) just need the extra strength of cast. 4.0's are prone to cracking between valves so that whole seat area is a weak spot.

In that thread from my last post (rebuilding and improving), they say they pitched the factory heads and went with "Clearwater Cylinder Head" off ebay... maybe more money than you want to spend, but that's another way to skin the cat and get out from underneath possibly suspect heads.

 

[Brain75]

search for GSI gave me this...

Search: 145 results found for "valve seat*"

GSI Auto Group Presents Limitless Possibilities in Luxury Auto. Serving the Western Carolinas | Shop our vast collection of auto parts, create your dream motorsport vehicle or schedule a service appointment today.

gsiautogroup.com

doesn't say if they are cast or...

 

[Shran]

1. They used crap material like someone said. Not hardened or something. Cheap china garbage. They wore out. Perhaps the other stuff they have done has had the same problem- but I am the only guy to actually figure it out?

2. The heads I got had hardened valves for propane. Like these were NOS heads, but for a propane application. The valves were hardened for that, and the seats in the 93tm were hardened too- which would typically be fine. However, the valves were moved to a 95tm head and regular seats were wore out by the hardened valves. I don't think this is a thing because I haven't heard of hardened valves for propane, only seats.

Just my opinion but machine shops only see failures. If you're talking about failures on a 30+ year old truck, how many people would fix it once, have a failure and pay to fix it again? You & I & a few other people but I think most would just junk the truck or make it someone else's problem.

Machine shops do mess up, I had my 2.3 rebuilt and it started knocking immediately. Bad rod bearing, they fixed it but there have been a lot of other weird problems that I have started to blame on them after ruling everything else out. I don't think they used a torque wrench on anything... I'm currently missing about 1/2 of the bolts that hold the oil pan on, the heads snapped off. That guy at the machine shop was the last person to touch them.

this thread (post #5) a guy says the original seats in a 4.0 are cast not sintered

Judging from a RockAuto search, you can get both for the 4.0. The sintered ones are more expensive - thought that was kinda weird.

 

[Kirby N.]

search for GSI gave me this...

Search: 145 results found for "valve seat*"

GSI Auto Group Presents Limitless Possibilities in Luxury Auto. Serving the Western Carolinas | Shop our vast collection of auto parts, create your dream motorsport vehicle or schedule a service appointment today.

gsiautogroup.com

doesn't say if they are cast or...

I was working from memory last night when I wrote GSI. I was really delighted when I got to my office and found a sticky note where I wrote the right initials for the inserts they said they use on the phone: SBI.

I found th here:

Product Details - SBI

I didn’t realize how universal seats are I guess?!?

 

[Kirby N.]

Just my opinion but machine shops only see failures. If you're talking about failures on a 30+ year old truck, how many people would fix it once, have a failure and pay to fix it again? You & I & a few other people but I think most would just junk the truck or make it someone else's problem.

Machine shops do mess up, I had my 2.3 rebuilt and it started knocking immediately. Bad rod bearing, they fixed it but there have been a lot of other weird problems that I have started to blame on them after ruling everything else out. I don't think they used a torque wrench on anything... I'm currently missing about 1/2 of the bolts that hold the oil pan on, the heads snapped off. That guy at the machine shop was the last person to touch them.



Judging from a RockAuto search, you can get both for the 4.0. The sintered ones are more expensive - thought that was kinda weird.

150% agree. Exactly my thoughts. They only see failures and they don’t see a lot of cases like mine. I also have had some bad experiences with shops lately- low attention to detail. And have some awful experiences with quality of parts. I think Amazon has really been deteriorating quality standards and conglomerate companies buying out all of their competitors and lowering the standards of quality some of these good old companies have built a reputation on. Looks at Yukon and Randy’s. It used to be the best in the business and now is owned by 4wp/ transAmerican and is the same crap in every other box.

 

[bobbywalter]

Hmm I would like to see the TSB that the machine shop is referring to. I don't think it is a case of computer/ head compatibility. I think it is head and block compatibility. But I could be wrong.

well....

it is all of those. one setup is more tolerant then another. i do not know because there are quite a few calibrations. there is a head block issue with compression both ways hi/low and there is definitely a fuel and timing curve differential across this platform...when these line up it is a problem. we found this out the hard way many times...and it was a hard catch early on.

quite the deal. i got lucky quite a bit and just try stuff...it will let you know if you are paying attention that it will grenade...most people dont know that though....my son was 14 or 15 when he broke the unit i was referring to, and all it needed was the fast burn pcm.