Hi, Had a few questions on replacing a lower intake manifold on a '90 Bronco 351W EFI.

How many hours should it take to do the job?

What if the lower intake manifold won't release after unbolting it? Where can I safely pry?

Do I use any gasket goop? What should I use, if I need to put something on the gasket or the faces of head or intake?

Does installing a performance intake manifold like a Edelbrock 3884 when you already have the performer 3881 make any difference in HP or torque?

Should I be replacing any other gaskets? Like the o-rings on the injectors?

Is it true that you can't do much about the different thermal expansion rates of the iron heads and aluminum intake? And is that the most probable reason of a coolant leak at 60k miles on the engine?

Thanks for any advice or experience you may want to share.

Ron

 

Well you've got to remove the upper intake,not sure about the 351 but on the 302 you'll need a long 1/4" extension to get to the torx screw in the center between intake runners.Just find a 1/4" socket the torx will fit in.While the upper is off I would clean the throttle body and the IAC ports.Also replace the thermostat and the bypass hose for the water pump and the two coolant hoses that go to the throttle body.If one of those puppies goes there goes all your coolant and maybe your engine(don't ask how I know this).I would put a small bead of silicone around the intake water passages.Get a good gasket with the rubberized coating,Fel-pro or Victor.Ditch the rubber end seals and put a GOOD bead of silicone on the ends.Especially around the corners where the head and intake meet.Since it's such a pita to remove everything I would pull the injectors and inspect them visually.The O rings and the pintle caps are cheap to replace.It might not be a bad idea to send them out for ultrasonic cleaning and flow checking.That should run around $100 bucks.Be careful when removing the old gasket that you don't get a bunch of crap in the lifter valley,cover it with something.Also change the oil immediately afterwards,you'll probally get some coolant spilled into the crankcase when removing the intake.You can do this in an afternoon,I would let the silicone set up overnight before adding fluid and starting up.With the stock heads I would'nt bother changing intakes.

Billy

 

Thanks for the advice Billy.

Regarding cleaning the TB valves, I'd like to share a BAD experience I had a while ago.
I cleaned them too good! If you clean the butterflys and the bore where the butterfly disks make contact at the closed position, like I did, you'll have air leak problems and a high idle. I found out that the factory puts some kind of sealant there, and when I cleaned the TB, it washed it off. A Ford mechanic told me about this & also told me how to fix it.
From the frontside of the butterfly disk, mask off the small gap. Then from the backside spray grey primer around the anular area surrounding the disk and tilt the TB so that the primer pools sligtly at the break-open area between the disk and bore. When the primer dries partialy, break open so it won't glue the butterflys in the closed position. Remove any masking on the fronTside.

I also had a failure of that long steel coolant tube that sits on top of the radiator. It feeds coolant to the TB. The problem is that the steel tube gets corroded from the outside (condensation) and then leaks. Ford charges about $50 for the part, because it has a swaged on hose as part of the assembly. I wonder if I can make make my own out of COPPER TUBING? Anybody tried this? Or is there a pressure problem that would affect life of the copper tube? Maybe use stainless?

Regarding the replacement of the LOWER Intake manifold if I have performance Heads. Yes, I have Ford GT-40 heads (cast iron) and JBA shorty headers. Someone told me that there wasn't too much benefit to a so called performance lower intake manifold even if I have a performance UPPER intake manifold like the Edelbrock 3881 and that the upper is going to do the most improovement. Edelbrock doesn't seem to make any claims of performance improvements for the lower intake by itself. They only show gains when used as a set.

The fly in the ointment here is that if I need to replace the lower intake manifold because of a coolant leaking passage, I think I can get a new Edelbrock 3884 for less that the Ford factory intake or even repairing the old one. So, what do you think?

About flowing the injectors; think I should do this if I use Techron every 6,000-10,000 miles? Techron seems to keep my MPG stable. BMW mechanics seem to like using it on beamers.

Thanks again for your inputs!

P. S. ANOTHER question:

How do you quantify the extents of damage to internal bearings, etc. if you suspect contamination of coolant (in the oil)? Like maybe examining the oil pump for wear?


Ron

Ron