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Cylinder Head Gasket Replacement
 
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Pelican Technical Article:

Cylinder Head Gasket Replacement

Steve Vernon

Time:

3-6 hours

Tab:

$60 to $300

Talent:

****

Tools:

Socket and wrench set, 6mm Allen, pry bar or large flathead screwdriver

Applicable Models:

Porsche 944 Turbo (1986-89)

Parts Required:

Head gasket kit

Hot Tip:

Spray all the hardware with penetrating oil

Performance Gain:

Proper power

Complementary Modification:

Flush cooling fluid

There are several signs that you are in need of a new head gasket. The most common amongst them is the mixing of your oil and coolant. If you have had a water pump or thermostat fail, and your car overheated, there is a very good chance you are going to be looking at performing this job, as the extreme temperatures associated with an overheated engine can damage both the head and its gasket.

Replacing your head gasket might be the biggest job you will attempt on your car short of rebuilding the entire engine. It is not a quick or easy job, but can be done by a DIY mechanic if you take your time, have the right tools and follow the instructions. This job can take a few days for a novice, so make sure you have the car in a secure and weather safe area before you start. You are going to be opening up the engine and may even be sending the head out for repairs, so you don't want to be working outside when it starts to rain.

I cannot stress this enough: get a digital camera and take lots of pictures before and during this job. Document wire and vacuum routing plus anything you feel unsure of. This can only help when it comes time to put everything back together.

If the head gasket has failed and you are going to all the trouble to replace it you really should have the head sent out to have it cleaned and inspected. Aluminum heads have a tendency to warp. If your head has warped, putting a new gasket on a warped head will not solve any problems and just cause the head gasket to fail again.

The physical act of removing the head is actually quite simple on the 951 eight valve motor. The real work is getting to the head! You will need to perform the following work before you can remove the head so please see all our articles on the following procedures.

Disconnect battery

Set engine at Top Dead Center (TDC)

Air filter and housing removal

Fuel injector and fuel rail removal

Cooling system draining and refill

Timing belt and balance belt removal

Distributor cap and wire removal

Intake manifold removal

Camshaft housing removal

Exhaust manifold removal though depending on your mounts you may be able to remove the head with the manifolds on

When you begin the engine compartment will look like this.
Figure 1

When you begin the engine compartment will look like this.

After you have performed the above work the engine will look like this and you are ready to remove the head.
Figure 2

After you have performed the above work the engine will look like this and you are ready to remove the head. Note: We have removed some components that you do not need to if you are only removing the head. You only need to remove what is listed above to replace the head gasket.

Use a 6mm Allen and remove the two bolts for the hose connection on the front of the head (red arrows).
Figure 3

Use a 6mm Allen and remove the two bolts for the hose connection on the front of the head (red arrows). This connection and the one below it block access to the front left nut, washer and stud (yellow arrow).

Remove the hose connection.
Figure 4

Remove the hose connection. Using the 6mm Allen remove the tow bolts holding the base to the head (red arrow).

There are two bolts on the front left side of the head by the temperature sensors.
Figure 5

There are two bolts on the front left side of the head by the temperature sensors. Use a 6mm Allen (red arrow) and 13mm socket (yellow arrow) and remove these.

There is a coolant line on the left rear of the head.
Figure 6

There is a coolant line on the left rear of the head. Use a 13mm socket and remove the two bolts (red arrows) and then the tube and gasket.

If you had the plugs in to protect the openings make sure to remove them now so they don't damage anything when removing the head (red arrows).
Figure 7

If you had the plugs in to protect the openings make sure to remove them now so they don't damage anything when removing the head (red arrows).

There are ten large 19mm nuts (red arrow) and thick washers (yellow arrow) holding the head on.
Figure 8

There are ten large 19mm nuts (red arrow) and thick washers (yellow arrow) holding the head on.

Use a 19mm socket and breaker bar to loosen the nuts on the head.
Figure 9

Use a 19mm socket and breaker bar to loosen the nuts on the head. Make sure to loosen the nuts crosswise and from out to in as with this illustration.

There are several places on the front and rear of the head that you can safely pry it up from (red arrows) to help break the seal between the head, gasket and block.
Figure 10

There are several places on the front and rear of the head that you can safely pry it up from (red arrows) to help break the seal between the head, gasket and block. Never pry anything between the head and block!

Since the head does not contain the camshaft or housing, it is relatively light and can be lifted by a single person.
Figure 11

Since the head does not contain the camshaft or housing, it is relatively light and can be lifted by a single person.

Remove the old gasket and look for any damage (red arrow).
Figure 12

Remove the old gasket and look for any damage (red arrow).

Clean and inspect the mating surface.
Figure 13

Clean and inspect the mating surface. The mating surface should be cleaned with a Scotbrite pad or plastic scrapers. Never clean the mounting surfaces with anything that could scratch the metal. While cleaning make every effort to keep debris from getting down into the water jackets (red arrow). If something gets down into the block make sure to give it a good flush before running the motor.

Inspect the head for damage and give the mounting surface a good cleaning using the same care as used for the block.
Figure 14

Inspect the head for damage and give the mounting surface a good cleaning using the same care as used for the block. If you had a blown head gasket or other issues you should send the head out for a professional cleaning and measuring. The heads can warp and putting a warped head back on the engine will just lead you to trouble and redoing the job.

The cylinder head can be attached with the exhaust manifolds attached.
Figure 15

The cylinder head can be attached with the exhaust manifolds attached. When installing the head make sure the new head gasket is positioned correctly and the head seats onto the locating pins. Install the two bolts at the front of the head and tighten to 15 ft-lbs. Next, put a light coat of clean motor oil on the stud threads. Install the washers and torque the nuts according to the pattern illustrated in the picture. The nuts should be torqued in three sequences while waiting approximately fifteen minutes between each sequence to allow the studs to stretch. Installation of everything else is the reverse of removal.

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