New Guy

[Rocket Man]

Hey everybody, new guy here. I make rockets @ www.binderdesign.com ....I've got a 91 EX that I've had for like 20 years and it has been to all of the big launches including the ones out at Blackrock, NV.

It recently started leaking coolant, but only when warmed up so I took it to Ford where they said it wasn't leaking and then charged me $100. By the time I got it home, it was leaking.

I determined it was coming from behind the motor but could not tell if it was between the intake or head gaskets, so I called Ford for a quote on both. They quoted $2,600 for some gaskets replaced, so I decided to do it myself.

That's when I found this site. This was the first time I've had to work on a water cooled engine, I've always worked on old air cooled VW's so I wanted to know what I was in for.

I did the tear down Saturday before last, no manual, just taking everything off that got in my way. Everything looked really good, so still don't know what gasket was leaking, but the head gaskets looked pristine, so I believe it was intake around the water jacket ports.

I dropped the heads off at the machine shop on Monday for new seals/resurface. Before I dropped them off, they warned me that the heads on these are usually not in good enough shape to reuse. Lucky for me, after inspection he said they were in really good condition, the best he'd seen come through there.

The only wear I could find that looked halfway bad was the rocker arms where the valve stems hit. I surfaced out the divots with a strip sander and polished them out, they were not too deep. Cylinder bores still had crosshatch, barely detectable ring wear. I've always used synthetic and changed @ 3K.

I reassembled last saturday, got it fired up and it ran quieter than it ever has. I'm assuming it has to do with the valve stems not having to settle into those divots, it was getting pretty clicky sounding, now it sounds like new.

Now I'm looking into why it has always idled @ ~1500. Did cleaning and check of TPS, MAF, IAC. Still have the same problem. Decided to do the paper clip method and got code 22, baro sensor. Ordered yesterday, going to pick up today.

Anyway, just wanted to say thanks for such an awesome site, i could not have gotten far without it! The EX is gonna be good for awhile for major maintenance, I might just have to treat her to a new paint job to look as good as she runs.

 

[Rick]

I'm glad you were able to get the info you were after. I take it that your leak stopped after resealing with new gaskets?

Your rocket site is very cool. My wife just helped one of her junior high students with a model rocketry science fair project. She had to source all of the materials for him.

 

[Rocket Man]

I'm glad you were able to get the info you were after. I take it that your leak stopped after resealing with new gaskets?

Your rocket site is very cool. My wife just helped one of her junior high students with a model rocketry science fair project. She had to source all of the materials for him.

Oh yeah...leak is gone I replaced the baro sensor today, no difference in idle, but the trouble code went away. Then I replaced the coolant temp sensor just in case that was causing my high idle. No difference. Then I started thinking, maybe my tach gauge is off. It doesn't feel like the engine is racing, but since it has always been this way since I got it, I don't know what it would feel like idling below 1000 RPM on the gauge. What I do know is that if I pull off the IAC plug when cold, it runs really rough so I believe that is working like it is supposed to.

It is running really well. I may just call it good. Thanks for checking out the rockets!

 

[Rick]

Check for vacuum leaks. A good place to look is at the hose and elbow that attach to the brake booster behind the master cylinder. There and everywhere else A vacuum leak will cause a high idle.

 

[Rocket Man]

Check for vacuum leaks. A good place to look is at the hose and elbow that attach to the brake booster behind the master cylinder. There and everywhere else A vacuum leak will cause a high idle.

Already did that one. I replaced the o-ring gasket a few years back when it was leaking. No vacuum leaks that I can find. In fact, I even unplugged each line one by one and plugged the manifold "tree" ports to eliminate each line. Then did the same test will all the lines off and rubber plugs over the ports. No change. I even blocked off the IAC with a solid gasket/plate. No difference when warmed up, obviously a bit rough when cold, but still idled above 1000 rpm when cold.

Throttle plate is closed all the way, no undue wear on the TB. Checked/cleaned/replaced sensors as needed. Getting no trouble codes now, but still high idle.

Tons of people with this same problem, unfortunately nobody posts what fixed it, so I'm assuming that they either give up, or just don't care enough to share the secret. I'm wondering if it is the PCM at this point.

 

[BrooklynBay]

Welcome to this forum! Since it was able to idle without stalling after you disconnected the IAC, it makes me think that air is getting bypassed into the system which is causing the high idle. Spray intake cleaner around various vacuum line connections to see if the idle changes.

 

[1Aauto]

Welcome to the site.

Tony

 

[Rocket Man]

Welcome to this forum! Since it was able to idle without stalling after you disconnected the IAC, it makes me think that air is getting bypassed into the system which is causing the high idle. Spray intake cleaner around various vacuum line connections to see if the idle changes.

I unplugged every vac line from the manifold and put rubber plugs on the fitting then blocked off the IAC holes with a solid plate with gasket, then covered the hole in the butterfly with electrical tape and it still idled @ 1200.

The only place left to leak air is the new manifold gaskets and I've sprayed around those to no effect.

It does smell rich with gas in the engine compartment.

 

[Rick]

The gas smell could be from the charcoal canister. They get saturated over time.

 

[Rocket Man]

The gas smell could be from the charcoal canister. They get saturated over time.

Yeah I can see that happening.

I just assumed it could be from cutting off all of the air to the vacuum ports on the manifold making it run rich.

I'm thinking it must be the gauge reading high. It is running so smooth and quiet I can't imagine it turning much slower. If I disconnect the IAC when the motor is cold, it will slow down and get real rough. No difference when it is warmed up.

Yet the lowest the gauge will read even when cold with the IAC plug off is around 1200 rpm.

 

[BrooklynBay]

Did somebody play with the idle stop screw?

 

[Rocket Man]

Did somebody play with the idle stop screw?

Nobody but me, as a last resort.

I wanted to make sure the butterfly was closed all the way so I backed it off until the screw didn't touch the stop. After I confirmed that it was completely closed and still didn't make a difference, I reset the screw so that the butterfly would not contact the TB when closed to avoid wear and sticking. Just using common sense, no feeler gauges.

Yes, I moved the "screw that shalt not be touched" lol. I also had to clean deposits off of the "throttle body that shalt not be cleaned". Since I'm the second owner I had to be sure someone before me had not goofed something up. Honestly at some point on an old vehicle, the TB will need to be cleaned and factory stickers don't scare me. I used a citrus based cleaner and soft shop cloth to avoid etching or scratching through the coating.

I don't have much faith on my local Ford dealership to have done any better. They can't even check an air filter without cross threading the PEM screw inserts in the plastic housing and ripping them completely out of the plastic. That's what they did the last time they charged me $100. And they kept my 4.0 plastic engine cover then could not find it and just said, "oh well, sorry".

I used to build VW engines and got tired of it, so on the Explorer I figured I'd pay for service. But every time they'd break something or leave something off, or not fix it but charge me anyway. So now I get to learn about the Ford 4.0 pushrod motor. If you want something done right, you do it yourself. Good thing for this site.

And next I plan on getting the air out of the ABS without their help or fancy tool. I changed the master cylinder without a manual or even looking it up. I did it like a VW and skipped the bench bleed, oops.