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head_gasket [2007/02/07 21:48]
whatsyourbeef
head_gasket [2016/08/18 20:27]
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-==== Changing the Head Gasket ==== 
- 
- 
-You will need: 
-  * New head gasket 
-  * New oil stem seals 
-  * New head bolts 
-  * Valve spring compressor 
-  * New exhaust manifold gaskets 
-  * Fresh engine oil 
-  * Rocker cover oil seal 
- 
- 
-Fistly drain the engine oil. See [[Oil change and filter renewal]] and drain the engine [[coolant]]. 
- 
-Remove the upper cam belt cover and ensure that the [[flywheel]] and [[camshaft sprocket]] are locked. 
- 
-Disconnect the [[HT leads]] from the [[spark plugs]] and any other electrical connections that would prevent removal of the [[cylinder head]]. 
- 
-Remove the rubber coolant hose from the [[thermostat housing]] and disconnect the fuel lines ensuring that relevant precautions are taken to minimise fuel loss. 
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-Next remove the [[rocker]] / cam cover by undoing the two bolts at either end, remove the two washers and and use a screw driver to lever the cover off 
- 
-Remove the cambelt, See [[timing belt]] 
- 
-Remove the [[exhaust manifold]], it is not necessary to remove the [[inlet manifold]]. 
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-Now undo the 10 head bolts in the correct [[Cylinder Head Bolts|removal sequence]] a few turns at a time once they are removed you can also remove the the [[rocker assembly]]. 
- 
-Now remove the cylinder head by rocking it gently backwards and forwards, take care when carrying out this procedure on [[alloy block]] engines as too much movement could displace the [[cylinder liners]]. 
- 
-With the head removed secure the liners in place using suitable clamps (alloy block engines only). 
- 
-===== Inspecting the Cylinder Head ===== 
- 
- 
-Inspect the cylinder head visually and with the use of a feeler guage for any cracks or pitting, if the surface is uneven the head will need to be machined or "​[[skimmed]]"​ by a professional. If the head is cracked or severly pitted this may not be repairable and a replacement part should be obtained. 
- 
-===== Valves and Valves Stem Seals ===== 
- 
-Place the head on a suitable work bench and use the [[tools|valve spring compressor]] on each valve in turn to depress the spring, undo the retaining nut and remove the spring and [[collet]]. Using a suitable set of pliers extract the [[stem seal]] from the base of the valve a replace with a new one (remember to add a smear of fresh oil to the seal), replace the spring and collet and tighten the nut. 
- 
-It may also be a good idea to [[re-lap]] the valves whilst they are accessible. 
- 
-===== Preparing to Refit The Head ===== 
- 
- 
-Prepare the mating surface on the bottom end by using a plastic or wooden scraper to remove any traces of gasket or other debris and clean the surface of the piston crowns with a solvent soaked rag (ensure you block the oil ways with some rag or tape to prevent debris entering the [[oil system]] as this could cause the pump to fail). 
- 
-Position the new gasket on the bottom end using the markings provided. 
- 
-Place the head carefully in position on top of the bottom end ensuring it is lined up correctly and replace the rocker assembly. 
- 
-Insert the new head bolts into each hole and tighten each one by a hand until finger tight and then tighten each one a full turn at a time in the [[Cylinder Head Bolts|following sequence]] until each one is torqued to 20nm/​15lbft:​ 
- 
-{{http://​i35.photobucket.com/​albums/​d163/​mark_fern/​Bolts.jpg}} 
- 
-Now working in the same order turn each one by the following angles: 
-  * Alloy block = 240' 
-  * Iron block = 120' and then a further 120' working in sequence 
- 
-Refit the rocker cover using a new Rocker Gasket with a smear of fresh oil. 
- 
-Refit the manifold using new gaskets. 
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-Refit the HT leads and electrical connections. 
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-Refit the upper coolant hose. 
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-Re-fill the engine with oil to the required level and re-fill the coolant. ​ 
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-It will now be necessary to bleed the [[coolant system]]. See [[Bleeding the coolant system]] 
- 
-NB: Ensure you remove any timing tools before attempting to start the engine. The engine may smoke for a short period after replacing the head gasket, due to oil or grease in the head or piston chambers being left in during work carried out. If this continues for a long period of time then there may be a problem with the cylinder head and should be looked at by a specialist or replaced all together. 
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head_gasket.txt ยท Last modified: 2016/08/18 20:27 (external edit)