In response to a request to post a collection on the replacing lower intake
gaskets on Vortec CPI engines....
Comments and corrections appreciated.
My experience is on a 99 (old style) Tahoe 5.7. Your experience may be
different. No warranty expressed or implied. Quantities may be limited. Void
where prohibited. Offer may expire without further notice. Yadda yadda
You should look up all the torque values in your manual. I can post mine
should anyone desire.
I bought the complete Felpro intake manifold set which was not complete at
all and very expensive. The Felpro design is great. I suggest buying the
gaskets you need and not the kit. I used the lower intake gaskets, the RTV,
and the fuel line o-rings...that was it. There was only one valve cover
gasket, but I took both covers off for cleaning. So I had to buy the valve
cover set. There is a part number for only one gasket, but at Pep Boys, it
was a dollar more than the pair and special order. The kit comes with the
upper plenum cover seal and the throttle body seal but no fuel line to
metering block o-rings so you are short if you need to take the plenum cover
off. I think it is also short 8 o-rings for the injectors, but I'm not sure
how those work because I didn't go there. Remember..this project is to fix a
coolant leak...not a air/fuel leak. The kit doesn't come with the thermostat
seal but your new thermostat should. No EGR gasket either. The EGR gasket
and thermostat are not needed to fix your cooling leak, but you should
replace your thermostat and clean your EGR ports while you are there. The
intake is more fun to work on at the bench than under the hood.
1. Disconnect negative battery cable.
2. Drain the engine coolant (if there is any left:) to at least a level
below the intake. If you have original coolant..drain it all and discard.
3. Remove the air duct from the mass meter to throttle body (cover the mass
meter opening with a shower cap or zip bag. Same for the TB or stuff with a
lint free rag.
4. Now is a good time to take lots of digital photos...in case you run out
of beer before you get it all back together.
5. Remove the upper radiator hose and three heater hoses. One of the heater
hoses has the quick disconnect that may crumble in your hands like powdered
Gatorade. Have a spare on hand if you don't want delays. The hose with the
quick connect can be popped out of its holder and folded back out of the
way. The aluminum bypass tube can also be loosened. I can't remember what it
gets in the way of...but some slop helps.
6. Remove the top radiator shroud and get it out of your way - especially if
you are going to remove the P/S pulley...discussed more later.
7. Remove the vacuum booster hose from the intake and rotate the check valve
in the booster so this hose is out of your way. Tuck it over by the booster
or down by the driver's upper control arm. This hose will constantly be in
your way if you don't.
8. Take the wires off the cap and remove the cap. Mark with a Sharpie where
the rotor is pointing - exactly. Also index the distributor shaft housing
with the hold down clamp or intake with a Sharpie. You might need a small
mirror to do this. Better to roll the engine to #1 TDC compression stroke
and line up the timing mark on the balancer with the indexer on the block.
With the cap off, you don't need to pull the spark plug. The rotor should
point "near" the cast "8" next to cylinder 1's electrode. You should mark
the difference between the rotor and the "8" so you can re-create it...else
you will probably throw a P1345 code upon restart like I did. I used a 13mm
stubby combination wrench for the distributor hold down bolt. There is not
enough room for a full size wrench...there is to break it loose but not make
quarter turns. An old fashioned distributor wrench in 13mm would work good
too, especially if you can put a ratchet/torque wrench on it to set the
torque. The distributor housing is plastic. Be careful when you put the hold
down clamp back on it. It likes to be in every position but the right one.
Use a small mirror to see it in the right spot before you tighten it down.
Also, book says the cap's screws are good for one time use only. Maybe you
could just put on new thread-lock paste - not drops. The housing is plastic.
If you haven't changed the cap and rotor before, now is the time and you
will get new screws with the cap and rotor.
9. Disconnect all electrical connectors and the necessary loom clips. I
disconnected the alternator's plug but not the main battery lead. Do not
attempt to remove the big wiring harness. Just disconnect everything and
move the little pig tails out of the way to a safe area. Bungee cord the two
big looms over the middle so that they are suspended above the intake. I
didn't bungee.but should have. The intake will slide out from underneath the
wires...hence my later term "re-entry."
10. Be careful with the tangs and such on the electrical connectors.they may
be old and brittle. (I did find them to be in better shape than those on my
'99 Navigator.) Note one of these loom clamps near the EGR to intake
connection is a nut on a nutted-stud fastening the plastic upper intake. The
stud will probably turn when you try to loosen the nut and you can't back up
the stud with an open end wrench. See notes at end on what I did. Also note,
all the electrical connections are different so you don't have to mark them.
My looms were stiffened from the heat enough to lay back into their original
positions. There is a ground wire on the thermostat cover. It has its own
11. There is a bracket that holds the wiring harness at the passenger side
rear of the engine. Don't bother trying to get it completely out of the
way. Just unbolt it where it is secured near the coil and then just lift it
up and out of the way. There is no need to attempt to unbolt it where it is
secured to the rear of the head. (I had no problem with this bracket but
here is a tip others have noted.... You will note though that the bracket
has a small tab right where it intersects the cylinder head/manifold area
that sticks forward over the intake. You need to bend this tab out of the
way, before you re-install the intake, otherwise it can interfere with the
manifold as you are moving it into position.) Also with respect to this
clip....if you are going to take off only one valve cover...removing the
driver side cover my help the intake slip under this tang.
12. Remove the Evap line from the passenger side solenoid. Don't break the
clip like I did. Push on the one side of the clip with the nipple "into" the
slot and pull on the hose just after depressing the clip. The hose should
slide right off. I broke the clip which is not available from parts. The
entire hose with EVAP test port was twenty-something at GM. If you break a
clip, post a request and I'll sell you one for $10;)
13. Disconnect the throttle cable and cruise cable. One has a clip. The
other just slips in a stop and the cable wraps around. Then squeeze the
plastic casing locks out of the bracket and tuck the two cables out of the
14. Remove the drive belt.
15. Remove the four A/C compressor mounting bolts. DO NOT DISCONNECT THE
HOSE ASSEMBLY. When the time comes, you'll slide the compressor FORWARD to
access the driver/front manifold bolt.
16. Disconnect the EGR pipe from the intake near the front and the bolted
hold-down bracket in the back. Don't remove the connection from the exhaust
line...that is not necessary and could lead to trouble.
17. Somehow disconnect the PCV valve hose. I pulled on the molded elbow on
the manifold connection so I could just swing the tube around and not have a
hole in the valve cover. When I did, it peeled apart like mozzarella cheese.
Replacement tube with valve was only $7 at GM. You might just pull the valve
out of the cover and remove the intake with the tube and try to remove it on
the bench. It is best to clear it out of the way for a smooth re-entry. Or
just buy the tube and valve the day before.
18. Disconnect the two fuel lines at the rear of the manifold. Do not remove
the fuel lines where they go into the upper plenum in the middle. Once you
have the distributor out, it's easy to disconnect the lines right back at
the firewall. You should replace the o-rings. One is big and one is small.
(The o-rings in the Felpro kit were black. I've never used black o-rings in
gasoline service. Usually, they are red. Hopefully black won't be a problem.
I should have picked up some red o-rings from GM like original and on my
'93. Black usually means Buna-N which is not the best choice for aromatics.)
19. Disconnect the electrical connector from the P/S pump if there is one.
My pump had no connector. There is a clip on the P/S bracket holding the A/C
compressor high pressure switch wire/loom. I delayed taking that loose but
eventually did and was glad. It allowed that entire pig tail with the A/C
clutch plug, temp plug, and ground to be cleared out of the way.
20. Remove the P/S pump pulley and loosen the P/S pump bracket nut and three
bolts on the front of the bracket. One bolt is hiding way down at the
bottom. Don't remove the two pump fasteners behind the bracket. Leave the
longest bolt in three or four threads so the bracket doesn't fall off. I
forget which bolt is the longest but you will figure it out. Two are only
about 2 inches long. The long bolt is 4+. This will allow you to slide the
bracket and the loose A/C compressor forward to get to the driver/front
manifold bolt. The compressor bolts might not have to be removed but it
helps to get the compressor more forward than the bracket.
Note: Cuda says you don't have to remove the pulley.just the upper fasteners
and pry the bracket forward when you need it. If Ian says it works, then it
does.but the newbie without a helper should borrow the P/S pulley tool from
AutoZone (the day before) and remove the pulley and the four fasteners. It
will truly give you more working room for cleaning and re-entry which the
newbie will appreciate. It takes only a few minutes to remove and replace
21. The intake gasket kit ships with only one valve cover gasket. You have
to take off at least one valve cover to get the intake off. The cover lips
sit over the intake so there is no choice but take one off and slip the
intake out from under the other. I removed the intake with the passenger
cover tilted to the side but then went ahead and tilted the driver's side to
the side as well for re-entry. It just looked easier with more space...and
it was. Plus, I took both covers off and gave them a good cleaning. That
black patina sure looks better than gunk in all the crevices.
22. Remove the intake manifold bolts and remove the intake. You will have to
pull up on the wire looms and slip the manifold out the front. I did it even
with the coil and ignition module on. Four of my intake bolts where corroded
to an hourglass shape. I went ahead and replaced all 8 bolts.4 bucks each at
GM. (Yeah, only 8 bolts! I don't know how many bolts a legacy small block
V8 has, but my 4.3z has at least 12. 8 on the vortec.another dumb mistake by
23. Clean the threaded holes where the intake bolts fasten. Clean the heads
and intake with a solvent saturated rag. If you scrape, be careful not to
scratch. Do not use abrasives, emery, stones, whatever, to clean the heads.
All the aggregate will fall into your valley/block and ruin your engine.
Before I started cleaning, I dabbed up all the antifreeze, fuel, and oil
from the valley area and cleaned the deposits from the low spots. Then I
cleaned the gasket areas on the heads and block. Then shop-vac'd the valley.
Then cleaned again with a lint free rag. Then I poured a quart of oil over
the entire valley to rinse any remains to the pan and leave a protective
coating. I covered the valley with heavy aluminum foil to keep the crickets
out while I slept. I also cleaned the manifold with solvent only. Maybe
there is a better way..like a cloth polishing attachment on a drill or roto.
It was pretty easy to clean even by hand. Plus I cleaned all the non-gasket
crevices just to make it look good and be clean. (I don't know if a shop
mechanic would do this .because I've never hired one. But I do it because my
dad taught me to. Yeah, he likes things clean.so I got to do the cleaning. I
guess scraping gaskets kept me out of his way. I'll be glad when my son can
scrape gaskets and chip welds.)
24. Check the intake faces with a straight edge like a nice level to be sure
they haven't warped.which is unlikely if you didn't overheat it. If you see
light along the straight edge, use a feeler gauge to measure and compare to
25. For most people, this job is to replace the lower intake gaskets to fix
a coolant leak. If you aren't having trouble with the upper intake, save
that job for another day. HOWEVER, there were a couple of bracket/loom hold
down nuts I had to remove that in turn loosened plenum cover studs. The
Felpro kit does not come with all the gaskets you need to remove the plenum
and the fuel pipes from the metering block. SO DON'T take all that apart
unless you need to and you have all the o-rings. Here is what I did on the
bench. Since a couple of the studs came loose, I went ahead a loosened all
of them one turn. Then took one out at a time, applied some loc-tite medium,
and returned that stud to near snug. After they were all done, I torqued
them in stages to spec in a crisscross pattern from the middle to the
outside. I did not replace the elastomeric gasket since I didn't pull the
cover.just loosened the bolts/studs. Had it been paper or such, I would
have. So far, so good.
26. With the intake on the bench, you might want to remove the EGR valve and
clear the carbon from the EGR passages. Buy the gasket the day before..it is
not in the set.
27. I pulled the intake off with the coil and module in place. They snagged
a few times on the loom so I removed them for re-entry. I went ahead a
removed the module from its holder and cleaned the heat sink with alcohol
and applied a thin layer of Ceramique heat transfer paste which is very
similar to what was there.unlike my 93 which had the remains of silicone.not
a metal/stabilized oil based heat transfer paste. Actually, silicone is not
a heat transfer compound at all.)
28. Remember to clean the threads of your intake bolts if they are not new.
29. Clean all the oil off the gasket surfaces with a light solvent like
thinner or alcohol. RTV won't stick if you don't. Follow the directions in
the Felpro box for applying RTV. They include Felpro brand black with the
intake gaskets. The gaskets have nipples on them to push into the heads so
they won't move around. The RTV is applied on the block and one-half inch up
the gaskets (both sides/both ends).
30. If you are re-using your intake bolts, apply loctite medium strength
threadlocker before you install them.
31. When you install the manifold you need to be able to move it into
position while keeping slightly above the gaskets and the RTV at either end.
Otherwise you can wipe the RTV off the ends and then you end up with a leak
after it's all together. One thing I might try next time is to put a small
stud in the passenger/front hole and a taller stud in the driver/second from
the back hole. The third bolt hole on the drivers side has a slot in it.
With the tall stud, you could index that hole to the tall stud then lower
the manifold indexing to the short stud on the passenger front. Then put the
other bolts in and finally swap the studs for bolts. The weight of the
intake is not very manageable when you're all hunched over.so either make it
fool-proof to install or get a helper or both.
32. Torque the intake in three to four stages in the proper order per the
33. By this time, you will be an expert and will know how and the order to
put it all back together. One thing to remember is to properly index the
distributor. If you miss it by more than plus/minus 2 degrees, you will
throw a P1345 code which means your camshaft sensor in the distributor is
not in sync with your crankshaft sensor. You will have to trial and error
adjust it clearing the code as you go or connect a scan tool with extended
data. Remember...no timing light required. The distributor does not control
ignition timing or advance.
Finally...before you start engine...change your oil and filter to get all
the crud out of your pan. If you are doubt about your cleanliness or didn't
drench your valley with a quart of clean oil..Drive your vehicle to Hooters
and back and change the oil and filter again!