Melted intake manifold !!!!!!!!!!!!!!!!

This is the follow-up to thread "BENT SPARK PLUG ELECTRODES".

Anyone melt their manifolds out there? How can one do this? Why would one do this? I miss aluminum inake manifolds...

Eureka....

Guess what gives a "lean mixture code" and misfiring in multipole cylinders (316)...

HOLES IN INTAKE MANIFOLD AND MELTED INSIDES!

I pulled the intake to start replacing the injectors ($38.00 at Advance Auto but they were out of them and did not show any in warehaouses but still cheap..)

I pulled the intake manifold and there's a normal amount of goo and black crud here and there and then I look into #6 and #5 runners in the manifold and notice what looks to be great gobs of black greasy spooge deposits... I stick my finger in to give it a wipe and it's as hard as..... PLASTIC! Then I see it... the runners are melted inside, some of the plastic has been sucked down past the o-rings, there are giant long vacuum extruded plastic sprues taking up a good deal of the inside, the base near the 0-rings is distorted and when I looked at the outside.... THREE HOLES ABOUT 1/16" DIAMETER! I had a stethescope with the open ended hose on it yesterday because I could have sworn I heard a vacuum leak.... I checked the manifold bolts for torque and they were okay so figured since I'm not familiar with this engine, it must be normal noise that sounds like a vacuum leak... WRONG!

Now it starts to make sense... The beauty cover that covers the throttle body was gone when I bought the truck... apparently some numb nutz must have been squirting highly flamable stuff into the intake and it backfired?

Or.... maybe ?

Now I'm not sure that I need to replace $300 - $400 worth of injectors...

I found the manifold online for $202 at Ford Parts Direct... the dealer qouted me $275 over the phone but they usually come down when I show up in person.....

Just how in the hell does one melt the intake manifold?

I'd imagine that valves and rings are tougher than ABS plastic at 1000 degrees.....

I took some high quality digital photos of the melted manifold...

Never have posted photos here.

Just "copy and paste" .jpg format into this box?

no you cannot just copy and paste the images must be uploaded to the internet first
Try a search for posting images


another reason why I like aluminum

Cant believe it melted!

I can't believe it melted either. Plenty of cracked ones, including the one on my mustang, but never melted.

Yeh, I can't believe it either....

As Billy Mayes would scream: "BUT WAIT!!! THERE'S MORE!!!"

Started looking at manifold even closer... It's a miracle this thing ran at all!

The rear two runners (5&6) got so hot inside that they damn near collapsed and with all the molten plastic that made all sorts of psychedelic plastice sculptures in side (from the air being sucked throughthe pinholes and molten plastic) what little was left of the runners, there might be at most a 3/8" x 1" opening through the length of those runners!

AND! I cleaned the engine because it looked like there was a concentrated amount of powdery tan dirt in the area of the throttle body and RH valve cover.. It's fire extinguisher powder! Didn't recognize it because it was tan, not white (and I CAN recognize that stuff because I discharged one onto a company loaner Durango once when my F350 was getting PM'd.. whadda mess!) So they apparently had the MAF and air cleaner hose removed from the throttle body when they saw flames coming out of the throttle body. The weird thing is that the engine had to be running for the vacuum to suck the pinholes and suck the runners down in size.... whadda num nutz!

pulled the injectors since I have the access and I'm going to find a reputable outfit to clean and test them... wish I still had that ultrasonic cleaner.. I cracked one of those little plastic ring shrouds on the end of one injector... Bummer.. now I have to replace ONE lousy injector because I was a klutz and dropped it... I also hate to replace just one without ccING THEM ALL TOGETHER TO MAKE SURE THEY ARE BALANCED...

So... hopefully by next wednesday night I should have the XLS running..... purrfectly... I hope.

Still all in all.. I have $3500 plus Indiana sales tax and a new manifold, fuel filter, plug wires and plugs, air filter and I still bought a clean 2002 xls for about $4300. I think the retail is closer to $9000... It just has to RUN when I get it back together....

Will post a final (hopefully) blog on this problem...

If you're looking to post pictures and you aren't elite, I recommend tinypic.com

You just upload, then copy/paste the code over. You can also pick how big you want the picture to be before it's uploaded.

Okay... here's a few pics of the xls and it's self imoliated manifold...

wow. first time I've seen this happen.

How could it get that hot? I'm not sure starter fluid would be hot enough long enough. What temp does that stuff become soft at?

wood1 said:

How could it get that hot? I'm not sure starter fluid would be hot enough long enough. What temp does that stuff become soft at?

Click to expand...

Chemical reaction, not heat.

So uh... lemme get this straight... the upper intake manifold is made of plastic?... What?... I am so confused..

Been in a few plastic extrusion and injection plants... You can extrude abs plastics at around 450 - 500 degrees F. Injection of abs, polystyrene etc takes a little hotter, 550 -600 F.

There is a little crispy charred plastic at extreme boundries of melted threads and tips indicating combustion.

This was definately HEAT/FIRE related. ABS is chemical (solvents) resistant.

The ABC dry fire extinguisher powder all over the top of the engine was the dead give-away.

My Take?

Goofus may have soaked intake walls with Gumout like cleaner, nearly stalled it, backfired, ignited and then they freaked out and shut it down which would have been major stupid because the intake would have been still saturated with the stuff but now no vacuum. They hit the outside of the throttle body with ABC extinguisher but not inside manifold (thank god) and the fire keeps coming back... dumb a$$ probably held throttle open too? Then they RESTARTED engine with fire still going on and plastic is becoming very soft and burning having been subjected to heat and flame for a few minutes. Starting the engine creates a big vacuum against soft plastic and sucks pinholes through exterior and narrows runners (see skinny runner with finger pointing at single hole).

rds

Okay...

Did a little chemistry check.

Gumout and other carb cleaners are according to MSDS, 70% xylene.

ABS plastic will break down with exposure to aromatic hydrocarbons and xylene is just such a compound.

Four things though..

For the runners to suck in on the sides, heat would have been the only element able to soften the plastic all the way through, evenly...

The intake is probably a tougher plastic than ABS which does not mean lower or higher temperature ranges than ABS

Ford would NOT have used a plastic that would not withstand exposure to carb cleaners

There was ABC dry fire extinguisher powder all over the area around the throttle body.....

It almost looks like a nitrous backfire but I'm sure that's not the case.

This is rediculous

Jakee,

Yeh that was what I thought... We've nitroused a few engines around here and that's one of the reasons we don't have ABC fire extinguishers in the shops.. It's preferable to use a CO2 extinguisher on something that is gulping air and worth a lot of money. And I've squirted a small block Mustang that got out of hand with a timing/fuel issue and the same car had a nitrous backfire at the drag strip under major load when the distributor sheared it's gear and the ball 'o fire was seen exiting the underside of the car halfway down the 1/4 and it looked like someone invited hell to visit. It was there then gone though.....

I'm thinking about just replacing all the injectors on this thing as a pricey insurance policy. I read in someone else's post that he had his injectors "cleaned and tested" and then one stuck open, filled the engine with fuel, he hit the starter and it was almost hydrolocked but five cylinders started and the one with fuel in it bent the con rod all to hell... clang clang clang clang clang... bad.

So maybe an injector stuck open? Doubt it since evidence points to dumb human involvement (powder where the throttle body should have been connected to the intake hose)....

Yeah, I don't think I'd do the injectors just yet unless you’re just set on buying new ones. I'm not saying it couldn't happen but your right, evidence is saying something else. If it were me, I'd do a good tune up, check and double check everything. Oh yeah, and replace the intake manifold. :

Just hot water extracted Sparky The Smelly Dog outta the interior.. Smelled like damp old dog in there... He spent time in the middle of the cargo area and the front passenger seat. He was NOT a clean doggie. Ick.... Lots of brownish/black extracted water.... ICK! Smells nice and looks new in there. Temperatures in the 70's here today so pushed it into the driveway with a fan in back blowing fresh air into it. Folks with kids and critters need vinyl or leather interiors.

I popped for a set of rebuilt oem injectors. After all the tear down I just want peace of mind after sticking all the bits and pieces back together. Dumba$$ me dropped one and demolished the little plastic shroud on the business end of the injector.... It's there for a reason and I didn't feel like breaking the other five off so the truck would have all 6 cylinders running like crap at near red line.....

So nothing more to report... I hope to have the new manifold and injectors by midweek next week and if my tired a$$ feels like messin with it after work, I hopefully will be up and running (good gawd smoothly I hope) by Friday...

2002 XLS, 4wd w/options and 74,000 miles, $3500 on ebay, $350 processing and tax fees, $450 for manifold and injectors, $50 for wires, plugs and filters = $4350 for a $8425 retail / $6550 trade-in value = $4075 saved.....

Not bad...

It just better damn well run perfect........

Melted Intake Manifold V 2.0 (backfire!)

Okay...

Bought new manifold, and the injectors came today so I popped them in and installed the new manifold. The rear most bolt is a major BI**CH!

Got everything reattached and started it. Ran like crap.

Luckily I only ran it for about 40 seconds. Weird 'chuffing' sound from rear of manifold. I touched the rear intake runner for #6 and it was HOT!

So... The original intake manifold melted from being driven while the #6 cylinder was backfiring through the intake valve. Hot exhaust gases in the intake manifold?

What the hell is going on here?

I've never opened up any of these SOHC engines so I'm pretty much clueless as to how this thing could be pushing hot exhaust gas through the intake. Bent intake valve? Valve lash adjuster stuck open? Cam wiped out? I also noticed that when cranking the engine it sounds like it spins fine on 5 cylinders @ TDC each but it sounds like it's over compressing one cylinder then goes back to spinning all but one cylinder okay..

1-2-3-4-5-ahhhhoommmph6 1-2-3-4-5-ahhhhoommmph6

The firing order is correct too...

Anyone have an idea?

I'm gonna call a friend that runs a 6 bay shop and see if he's up to speed on these 4.0 SOHC engines and send it down the road on a hook.

Boo Hoo... I was really hoping to get away with the new manifold, new injectors and a major tune-up but it's not looking that way.

rds

$800 in labor to R&R engine
$700-$1200 for a salvage engine

I'm starting to wonder if I should have found a low mileage Gen II 4.0 pushrod Explorer instaed of this Gen III SOHC...