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Though I've done a handful of small auto repair and maintenance things myself, I've never touched the engine and thus I have a potentially newbish question...  I have a 1986 Lincoln Town car that I am replacing some vacuum hoses on.  I can't directly access those that run under the top of my engine as seen here...
http://i16.photobucket.com/albums/b23/grgurmg/efi_engine.jpg

My question is, what exactly is that grey top part called and what should I know about removing it past simply unbolting it. That is assuming that can be done easily, which if not my alternate course of action I suppose is to remove the hood so I can better reach in and under the backside of that top.  

that is the upper intake plenum....

you are going to find that there is a dual size hose from under the back that runs over to the black device on the firewall toward the left side of the picture.. thats actually the MAP sensor..  manifold air pressure..


there is another dual sized vacuum hose from a hidden spot under the front that hooks to the rigid plastic hose that leads over to the front passenger side corner of the engine compartment..  hooks to the carbon vapor canister..

you will almost always need one of these...




Felpro/Intake Plenum Gasket
For your 1986 Lincoln Town Car 5.0L FI 8cyl
Part Number: MS94555
Alternate Part Number: AMS94555


you may also want to replace the throttle body gaskets.. there are 2 different versions.. since you appear to have the regular 50 not the HO 50..


if you go to autozone.. for some reason.. these are listed under the exhaust page...
Felpro/TBI Base Gasket
Part Number: 70261
Alternate Part Number: 66-0302
Notes: Throttle body to EGR valve adaptor.



Felpro/TBI Base Gasket
Part Number: 72540
Application: With standard engine
Notes: EGR valve adaptor to plenum.

this is for the air bypass valve...

Felpro... idle air bypass valve gasket..
Part Number: 71216



with the upper plenum off.. you will want a PCV valve grommet

Part Number: 42327
Dorman - HELP! - Carded. PCV to valve cover.

this is down below the PCV grommet its the PVC filter.. it actually stops backfires from going down the PCV hose and igniting the crankcase vapors in the oil pan and valve covers..   the problem is these filters clog..  restrict PCV flow.. cause the gaskets to leak...



Part Number: 47064
Dorman - HELP! - Carded. Crankcase breather filter.

you will probably want to search out the black adaptor for the hoses under the intake...


3/8 X 1/4 is the size you will probably want..
Dorman/AutoGrade 8 pcs. hard straight vacuum tubing connector assortment
Part Number: 47308

you will probably need several feet of 7/32 vacuum hose.. and some 3/8 fuel line to use at the hidden nipples under the front and rear of the plenum.. and then adapt them down to connect to the MAP sensor and to the rigid plastic hose to the carbon canister..

please be careful with the throttle valve cable...     thats the one that goes to the transmission.. when you free it to remove the upper plenum.. DO NOT CHANGE THE ADJUSTMENT..    if you do.. it is a precision adjustment..  get it wrong.. you CAN burn out your transmission in 2 blocks..


why do i know all this.. because i used to work on a LOT of them...    been there done that a LOT of times..  

i have a few more things to check...   keep checking back././


there area 2 hidden bolts under the black  5.0 panel on the top of the plenum...  

Wow, thanks for the quick detailed response. I'll definately check back.

Seems like more work then I planned, but not beyond me.  I'm aware of the MAP, in fact the hose going to it is the one that definately needs replacing, very dry and cracked.  

other things to check....

the air injection manifold..



there are 2 different versions of this..  

these get corrosion leaks in the tubing..

allowing uncommanded air into the exhaust stream where it fools with the oxygen sensor  readings...

this is also the air injection check valve.. these rot out and the check valve fails.. allowing hot exhaust gasses to flow backwards through the hose and melting the diverter valve .




there are 2 different diverter valves on the back of the smog pump...

this one rarely goes bad...  check to see if you can apply and hold vacuum on the upper fitting...


the picture above it called the TAB valve..
Thermactor air bypass valve..


the TAD valve is no longer available.. for the exact fit version as far as i can tell.. i searched for one for a long time..  found a similar valve off a 90 town car that worked...

this is one of the diverter valves that look like it will work..



this is a TAD valve.. thermactor air diverter valve..
at AZ    Duralast/Diverter Valve
Part Number: DV44

test the vacuum diaphragm for operation.. it should NOT leak..

when you don't have vacuum applied.. the air flows from left to right through the valve...        when the vacuum is applied.. the air flowing in from the left is diverted out the bottom opening ONLY..    without vacuum.. there should be NO air leakage..

why am i going through all of this.. because.. i have done it so many times..   you will also want to verify the smog pump creates significant air flow and pressure..

when the tubes or check valve are leaking.  or when the diverter valve is leaking air into the tubes shown above..

this sends uncommanded air into the upstream exhaust.. screwing the exhaust gasses up and fooling the computer into dropping into default .. and reducing the fuel economy and the power..

you will HAVE to run a KOEO and a KOER test and verify that you can pass it without any codes other than pass 11..

with these parts working properly..   you can get close to 25MPG in these big cars..  

i have also had struggles with the vacuum hoses in the harness separating..  

had problems with the EGR valve.. and the egr position transducer..  to where i had to add a second gasket under the transducer to get the push rod length correct so it would NOT set a code..

perhaps a moderator might eventually change the name of this thread to 86 town car 5.0 upper intake plenum  or something more suitable..  than engine top..  

this is closer to what the original TAD valve looks like..



Duralast/Diverter Valve Part Number: DV42

~~~~~~~~~~~~

there is also this one.. but the hose size is wrong...



Duralast/Diverter Valve        Part Number: DV51  

Howdy,

First off I want to thank you again, waynep7122, for all the help. I ordered most of the parts awhile ago, but due to my schedule, the holidays, and brake job I had to do on my girlfriends car, I didn't really get a chance to work on the Lincoln until recently. As far as parts, aside from the gaskets and such I bought a new PCV filter, grommet, and a PCV Valve.

Today I finally got everything dissembled. Man is it a mess in there. I'm gonna really clean out the plenum and throttle body good while it's off. Will take a look and test/inspect other components once everything is cleaned up. Here's some pictures...






What I'm wondering now is what to do about the gunk further down into the cyclinder.  Should I bother pulling things apart more to remove and clean the upper cyclinder.. or should I just reassemble from where I'm at now and try some Seafoam spray to get at the rest.  I'm leaning towards the first option.

Also, one other thing that broke that I not quite coincidentally already had the part for was my heater control valve.  I've been eyeing it as a suspect to my lack of heat, for awhile now so ordered it recently.  Low and behold while I was sorting through my vacuum tubes the damn thing just fell apart on me for no reason. My only issue with that otherwise easy fix is I'm a little iffy on the two hoses that connect to it. The lines that were there aren't intact.



Haven't inspected too thoroughly, but I'm not entirely sure where I should connect the hoses... am I just tapping them into a vaccum line or do they connect by the firewall somewhere or what?  

And by heater valve, I think I really mean TBL (Thermal Blower Lockout) switch.  

good to hear from you...

you DON'T have to clean the inside of the various manifold passages..

you might want to carefully.. so you don't contaminate the Throttle position sensor with any liquid solvent .. clean the throttle body bore and throttle blade...  

i would also like to warn you about using rotary cleaning equipment ..  spinning wire brushes.. spinning sand paper discs... spinning scotch brite pads...   ARE really dangerous around engine parts..   the abrasive gets thrown into areas where you don't see...   its like putting Beach sand into the engine oil..  its going to get into the engine.. most people don't understand.. do to the cold oil start ups.. and high Rpm operation .. oil filters DO NOT clean 100% of the oil every pass through the oil pump...    the oil pump never sees filtered oil...  so ANY debris that gets into the engine will get to the main and rod bearings..

invest in a 6 or 7 buck 5 way painters tool .. Hyde makes the best ones i have found..  and a diamond file.. so you can keep the edge perfectly straight and sharp..   stokes along the angled side to sharpen it..  then a single stroke usually flat to take the curl off the back of the blade will leave you with a tool that won't dig into aluminum ..  if it gets a bur.. sharpen again.. only takes 30 seconds..


the vacuum hoses to the thermal lock out switch... are really important..  without them being perfect..  the automatic temp control of the heating and ac system WILL NOT work..

i worked on an 83 Tbird.. the owner a pilot needed the AC to work.. spend 900 bucks at a repair shop ... replaced all kind of parts..  including the thermal lock out..  but still could NOT get the automatic temp control to do anything but blow hot air..  took me about 10 minutes to verify that there was NO  vacuum signal to the actuators under the dash..  i replaced the hard line with fresh hard line from the parts store..  and it worked great..  i did have to change it all the way through the firewall.  getting in behind the glove box to the top of the ac box to connect it..  

you may also want to smear the plenum gasket with some grease to prevent it from sticking to the surface..

be careful that it gets evenly tightened down...



Dorman/AutoGrade 1/8 in. dia. x 3 ft. length multi-purpose tubing Part Number: 47417

you should be able to work a pin or sharp probe into the rubber connectors to loosen the glue grip to free the broken vacuum line...

these are also available.. in small packs.. or mixed packs.. or elbows..


Dorman/AutoGrade 6 pcs. soft vacuum tubing connector assortment Part Number: 47432  

i would also like to advise you about using turning cleaning equipment ..  rotating line styling brushes rotating emery document dvds rotating whiskey brite shields are really risky around power plant parts. The rough gets cast into areas where you don't see its like putting Seaside fine sand into the power plant oil its going to get into the power plant.  
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So.. I've been about a day (hour or two) from getting everything back together and starting her up for awhile now. Cleaned things, replaced tubes, gaskets, flushed everything, a completed job right over the horizon...

... then Christmas came, then I got sick for a couple, then the temperature dropped...  Any advice on freeze plugs?

There was still water left in my system when the temperature dropped just a hair below freezing yesterday.  I definately popped one plug and hopefully nothing's cracked. I'm shooting to get some rubber seal replacement plug(s) from AdvanceAuto.. the ones with the nuts.  I'm sure it'll be the common recommendation to replace all the plugs, but if I can get away with replacing just the popped one and any others that show obvious leaking, I might do that for now.

What are the chances I'm going to be able to get the replacement plug in without removing half a bazillion things? Haven't gotten a chance to thoroughly inspect underneath yet.  

DOH!!!! as homer simpson would say...

freeze damage is hard to spot...  

rubber freeze plugs are usable..  i don't personally like them...  the hole has to be clean.. and TOTALLY DRY when you install it.. or it WILL pop out.. leaving you complete drained of coolant .. and you might not notice till its way too late...

the least expensive way to buy freeze plugs is in a freeze plug kit...  could be either part number at various stores..


Dorman/Freeze Plug Kit
Part Number: 02663
Notes: Brass plug kit

Dorman/Freeze Plug Kit
Part Number: 567-009
Alternate Part Number: PE-108-B
Notes: Brass plug kit  

to make it easier.. dorman also offers Pilot seal freeze plugs...  they have 2 steps on the sides.. so you can get it in the hole part ways..  then drive the freeze plug the rest of the way..

some stores will rent you freeze plug driver tools..

getting out freeze plugs requires special thinking..

knocking them in.. without damaging the block surface area.. turning the knocked in freeze plug almost half a turn and pulling it part way out the hole...  then using a prybar or a pair of channel lock pliers to yank the freeze plug that is turned straight out..

be sure to clean the bores with a spinning wire brush..

use your finger to see that there are NO burrs to the bore..

i normally have to hold the engine up with a engine/transmission support bar like this one from harbor freight..



this sits on the inner fender lip.. or on the top of the fenders depending upon the design. but close to the hood opening..  so you can lift the engine off the motor mounts to get them out of the way to get access to the motor mounts behind them..  

you will want to pick up a tube of this...


permatex #1        NOT SILICONE... NOT anything else.. this is the stuff..



Permatex/3 oz. tube Form-A-Gasket no. 1 sealant
Price: $3.49


Part Number: 80008
Alternate Part Number: 1BR

Features & Benefits

Fast-drying, hard-setting sealant designed for sealing rigid materials and flanges, or patching holes and joints where permanent assembly is desired resists common shop fluids and fuels.
Part Number: 80008
Universal Fit: Yes
Application: Freeze plugs, threaded connections, manifold gaskets
Temperature: Temperature range -65°F to 400°F (-54°C to 204°C)