I have an 88 with the 5.0, it has gt40 heads and cobra intake, 70 mm throttle body and maf. Lunati hydraulic roller cam and roller lifters, and MSD ignition. Now ive only had the car for about 2 months, when i got the car it had a surging idle from probable 700-1100 rpm. the other week i reset my idle and tps and replaced the fuel line that connects my fuel rails. the next day my car started running funny and i noticed oil coming out of my intake. so come to find out it was coming through the cranck case breather. so i looked it up and ended up installing an air seperator and within 20 min of driving the thing is full of oil. So my question is what could be causing my crank case pressure so high? and could i just plug where my pcv valve is and run breathers on my valve cover?
A Few Questions, I Need Some Help
- Thread starter Andiv5000
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Check the PCV valve and make sure it isn't stuck. I would replace it if you haven't already done so. Clean the screen that is under the PCV valve and replace the PCV grommet while you are at it.
If you have so much pressure in the crankcase that a new PCV valve grommet and cleaning the screen doesn't fix it, that means you have piston rings that are not sealing properly or a blown head gasket. It is time to do a compression test to check the cylinder condition.
Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading. Your local auto parts store may have a compression tester to rent or loan. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.
With the engine warmed up, remove all spark plugs and prop the throttle wide open with a plastic screwdriver handle between the throttle butterfly and the throttle housing. Crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 PSI. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.
I generally use a big screwdriver handle stuck in the TB between the butterfly and the TB to prop the throttle open. The plastic is soft enough that it won't damage anything and won't get sucked down the intake either.
A battery charger (not the trickle type) is a good thing to have if you haven't driven the car lately or if you have any doubts about the battery's health. Connect it up while you are cranking the engine and it will help keep the starter cranking at a consistent speed from the first cylinder tested to the last cylinder.
If you have so much pressure in the crankcase that a new PCV valve grommet and cleaning the screen doesn't fix it, that means you have piston rings that are not sealing properly or a blown head gasket. It is time to do a compression test to check the cylinder condition.
Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading. Your local auto parts store may have a compression tester to rent or loan. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.
With the engine warmed up, remove all spark plugs and prop the throttle wide open with a plastic screwdriver handle between the throttle butterfly and the throttle housing. Crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 PSI. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.
I generally use a big screwdriver handle stuck in the TB between the butterfly and the TB to prop the throttle open. The plastic is soft enough that it won't damage anything and won't get sucked down the intake either.
A battery charger (not the trickle type) is a good thing to have if you haven't driven the car lately or if you have any doubts about the battery's health. Connect it up while you are cranking the engine and it will help keep the starter cranking at a consistent speed from the first cylinder tested to the last cylinder.
Thanks for the reply. I have already changed the pcv and grommet, I just picked up the screen yesterday I had to order that because no one carrys them near me, so I still have to put that on. I will be doing the compression test this weekenrnd. If I have a bad head gasket does that mean I should be getting coolant in my oil, or not necessarily? Because I know my oil is clean.
It depends on where the gasket blows out...If it towards the push rod area, you would not see any oil and water mixing, but you would have extra blow-by in the crankcase.
mikestang63
SN Certified Technician
do a screw in compression test
squirt some oil in the cylinder
do the compression test again
if the reading goes up- its your rings
Bad rings will give you blue smoke when driving
BAd valve guides is blue smoke on start up
squirt some oil in the cylinder
do the compression test again
if the reading goes up- its your rings
Bad rings will give you blue smoke when driving
BAd valve guides is blue smoke on start up
mikestang63
SN Certified Technician
Count yourself lucky that it was a easily diagnosed and will be a relatively inexpensive fix. Spend a couple of hundred dollars on gaskets and fluids razor blades and cleaning suplies and you're back in the game. 
Count yourself lucky that it was a easily diagnosed and will be a relatively inexpensive fix. Spend a couple of hundred dollars on gaskets and fluids razor blades and cleaning suplies and you're back in the game.
Cylinder head removal & replacement
Revised 25-Aug-2014 to update parts list
Plan on 3 days to do the job if you haven't done it before.
Day one gets the heads off in 4-6 hours. Remove the A/C compressor mount bolts and move the compressor out of the way. The A/C compressor swings out of the way without disconnecting any of the lines or losing any refrigerant. Mark all the electrical, smog and vacuum lines with tags to help you remember where to re-connect them. If you have a digital camera, take several pictures.
Day two gets all the gasket surfaces scraped off extra clean and the heads dropped off at the machine shop if you are going to have them reconditioned. Time here is another 4-6 hours. Whatever you do, don't skimp on cleaning the gasket surfaces. New gaskets need to seat against bare metal and not the residue left from the old gaskets in order to seal leak free. This is the most time consuming and tiresome part of the job. Look for little things that need to be replaced like the short hose from the thermostat hosing to the water pump, damaged vacuum lines and hose clamps that are rusted or broken.
Day three starts when you get the heads back from the machine shop. This is the time to pick up all the little odd pieces you found needing replacement on your day two inspection/cleanup. Plan on 6-8 hours to reinstall the heads and reconnect everything. Plan on an additional 2 hours to troubleshoot/adjust everything.
Now for some practical tips:
Tools: a good torque wrench is a must have item. A razor blade scraper that holds a single edge razor blade from Home Depot or Ace hardware is another handy thing. Get a Chilton or Haynes shop manual - you'll need it for the bolt torques and patterns. The intake manifold has an especially odd pattern.
Diagram courtesy of Tmoss & Stang&2birds
The bolts are torqued down in a 3 step process.
Step 1 8 ft/lbs
Step 2 16 ft/lbs
Step 3 23-25 ft/lbs
You'll need access to a timing light to set the timing after you re-stab the distributor. Look in the A/C repair section for the fuel line tools. They look like little plastic top hats. You will need the 1/2" & 5/8" ones. The hat shaped section goes on facing the large part of the coupling. Then you press hard on the brim until it forces the sleeve into the coupling and releases the spring. You may need someone to pull on the line while you press on the coupling. Put some motor oil on them when you put the line back together.
Whatever you do, don't skimp on cleaning the gasket surfaces. New gaskets need to seat against bare metal and not the residue left from the old gaskets in order to seal leak free. This is the most time consuming and tiresome part of the job. Look for little things that need to be replaced like the short hose from the thermostat hosing to the water pump, damaged vacuum lines and hose clamps that are rusted or broken.
Put some cardboard in the lifter valley to help catch the gasket scrapings. Have a shop vacuum handy to suck up the scrapings and any coolant that leaked into the lifter valley.
Plan on cutting the thermostat to water pump hose, or removing the thermostat housing. Also plan on removing the distributor to get clearance to remove the intake manifold. Remove #1 spark plug, stick your finger in the spark plug hole and crank. When your finger gets air moving past it, stop cranking. Turn the engine until the timing marks line up with the pointer. Now you can pull the distributor out. Be sure to put a rag or cap in the block where you removed the distributor. It will save you trouble if something falls into the empty distributor hole.
My favorite trick that saves time and effort is the stay in place gasket. Be sure that you scrape (don't use a wire brush) all the old gasket material off, then clean all the surfaces with acetone or MEK.
When the surfaces are clean, use weather strip adhesive on the head to manifold surface, and on the side of the gasket that mates to the head. Follow the instructions on the tube or can and when it gets tacky, press the gasket down on the head.
Clean the area where the rubber rails mount to the block in front and in the rear with more acetone or MEK and do the same trick with the weather strip adhesive that you did to the heads.
Coat the rubber seals and the gasket area around the water passages with Blue Silicone gasket sealer and put it together. Whoopee! no leaks, and no gaskets that shifted out of place.
Get a tube of anti-seize and coat all the bolt threads and under the bolt heads. That will help insure even torque when you tighten the manifold bolts. Plan on re-torqueing them after a week’s worth of driving
The cylinder head bolts are reusable, but some new ARP bolts are a better plan. Be aware that the ARP bolts have a radiused shank under the bolt head. The ARP washers have a matching radius machined into them. Be sure that the machined radius of the washer is fitted next to the machined radius on the ARP bolt heads. Forget this little fact and you will never get the head bolts to torque down properly.
Coat the underside of all bolt heads with anti seize and the threads of the long bolts. The short bolts thread directly into the water jacket and need a different treatment. Use Teflon Pipe dope on the threads of the short head bolts. It will prevent any coolant seepage from around the threads. You can get the Teflon pipe dope from the hardware stores, Home Depot or Lowes.
Fuel injector seal kits with 2 O rings and a pintle cap (Borg-Warner P/N 274081) are available at Pep Boys auto parts. Cost is about $3-$4 per kit. The pintle caps fit either injectors with a pin sticking out the injector end or 4 with more tiny holes in the injector end. The following are listed at the Borg-Warner site ( BWD - Home ) as being resellers of Borg-Warner parts:
Parts Plus - Premium Auto Parts & Accessories or Auto Value / Bumper to Bumper Quality Parts & Service - Home of the Aftermarket Auto Parts Alliance Group or Tires, Auto Parts Stores, Brakes & Automotive Parts | Pep Boys or Federated Auto Parts - Automotive Aftermarket
Most of the links above have store locators for find a store in your area.
Use motor oil on the O rings when you re-assemble them & everything will slide into place. The gasoline will wash away any excess oil that gets in the wrong places and it will burn up in the combustion chamber.
Putting the distributor back in is fairly simple. Pull #1 sparkplug, put your finger in the sparkplug hole,
crank the engine until you feel compression. Then line up the TDC mark on the balancer with the pointer
on the engine block.
The distributor starts out with the #1 plug wire lined up at about 12:00 with you facing it. Align the rotor
to about 11:00, since it will turn clockwise as it slides into place.
Align the distributor rotor up with the #1 position marked on the cap, slide the distributor down into the block, (you may have to wiggle the rotor slightly to get the gear to engage) and then note where the rotor is pointing. If it still lines up with #1 position on the cap, install the clamp and bolt. If not, pull it out and turn 1 tooth forwards or backwards and try again. Put the #1 spark plug back in and tighten it down, put the clamp on the distributor, but don't tighten it too much, as you will have to move the distributor to set the timing. Note that if it doesn't align perfectly with #1 position, you can turn the distributor until it does. The only problem is that if you are too far one way or the other, you can't turn the distributor enough to get the 10-14 degree optimum timing range.
At this point hook up all the wires, get out the timing light and start the engine. Set the timing where your car
runs best. Don't forget to disconnect the SPOUT jumper connector when you set the timing, and plug it back
in when you finish.
The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8
Consumable items:
head gaskets or head gasket kit
Rocker cover gaskets
Upper manifold gasket
Fel Pro 1250 or equal lower manifold gasket set.
Exhaust manifold gaskets.
Short formed hose between thermostat hosing and intake manifold
6 ft 7/64" or 1/8" vacuum hose
2 ft 1/2" heater hose
1 1/2 ft 5/8" heater hose
Blue Silicone sealer
Spray can weather strip adhesive to hold manifold gaskets in place
Acetone or MEK to clean gasket surfaces
1 gallon straight antifreeze (same price as 50/50 mix, but a 90 cent gallon of distilled water makes it 2 gallons at a cheaper price)
1 gallon distilled water
ARP antiseize or equal for the bolts
Teflon Pipe dope
4 each 3/4" hose clamps (spare item in case the old ones are bad)
4 each 1/2" hose clamps (spare item)
Machine shop charges will vary - figure $275-$350 to have heads checked for cracks, cleaned, surfaced, valves ground, valve guides reconditioned, valve springs checked and bad springs replaced.
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.
Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg
HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif
TFI module differences & pin out
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif
Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif
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