Cylinder Head Removal/Coolant change

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Cylinder Head Removal/Coolant change

Postby Gman » Thu Jun 04, 2009 5:19 pm

A little time consuming but pretty easy on these bikes.Please have a manual either hard copy or downloadable version available.Print out pages if need be.

Remove seat and tank.
Remove Battery side panel and disconnect earth wire.
Remove Rad cap.
Pull Overflow pipe from rad.
Place washing bowl or similar under the rad(Old Oil bottle cut out with cap on can be used for this and oil changes),


Remove Front Rad guard if fitted so as to be able to remove bottom drain plug and rubber washer.(Don't over tighten when re-fitting,only decent hand tight).

Loosen upper and lower Rad hoses.Remove Radiator.
Remove front exhaust header pipe/s
Remove Fan guard and cooling fan.
Remove Front Engine hanger.
Remove Metal Water pipes and knuckles on side being worked on or both if doing both heads.
Disconnect carbs at the engine side of the carb boots.
Find and remove 10mm Cylinder jacket bolts to allow full draining of coolant(Between the fan blades here.One on each cylinder left and right.


Remove Head covers.
Remove the two 10mm long bolts that secure the Coil rubber DAM on top of the engine if fitted(These only have a low torque rating of around 10 Ftlbs max when refitting).
Remove the four Cylinder head bolts.
You may have to,"Crack" the seal between the head and the block.I use a cheap rubber Camping mallet.
Once the head is off you should remove/pry the rocker assemble off.You will need this off to make refitting easier.Remove the push rods and clean them through with Carb cleaner or the like and put them somewhere safe.

Once you have done the work on the head you should clean out ALL the four Cylinder head bolt holes.I use twists of toilet paper pushed into the holes until they are totally free of any fluids.Failure to do this will lead to a Blown head gasket not far down the road.

Clean all Head and block surfaces prior to refit.You can use Scotchbrite with Carb cleaner or thinners to remove old gasket/sealant debris or if stubborn paint some paint stripper onto the parts and leave to melt them for ease of removal and Paint stripper can be used on Carbon on the head/s to soften it and then scrub clean with Scotchbrite.
If the head gasket is in serviceable condition it can be re-used with some Head gasket sealant like Blue Hylomar.This should be applied on both mating surfaces with a small pencil brush and then all excess wiped clean and left to cure for 10 mins.
On top of the Cylinder there is a small Oil pressure regulator with a small O-ring around it.This must be present and inserted the correct way up.The small pipe part of this should face down into the engine.

When happy with the cleanliness and sealing if required offer the head to the block onto the two locating dowels.These sometimes come off into the head.I prefer them into the block but it's not important so long as both are present.You may have to tap the head down with the Rubber mallet.

When the head is semi- seated now you can re-fit the push-rods.This is why we removed the Rocker Assembly.Now re-fit the rocker assembly and make sure you seat the push-rods into the bottom cups correctly and the align them into the top cups of the Rocker assembly.

You can now insert the Cylinder head bolts.There is a correct Cross Hatch tightening procedure for these bolts and they should be done in increments.

Bottom right
Top left
Bottom left
Top right.

I use Increments of 5 Ftlbs Starting at 10 Ftlbs on my Torque Wrench and go around the pattern e.g 10/15/20/25/30/35.
This makes sure you don't warp the heads when tightening.

The Final torque settings for CX/GL500s is between 36 and 40 Ftlbs.I do mine to 38 Ftlbs.
Check the tappets clearances.

Once you have refitted all the other components you are ready to Run the engine you MUST bleed the coolant and then re-check the Head bolts torque.

With the tank on but pulled back and the Rad cap still off run the engine until normal operating temp but don't over rev the bike/engine until you see coolant flowing over the inner rad fins.This will allow any trapped air in the system to bleed out and also the coolant level may drop so you can top it up.

Then let the engine cool to stone cold and re-check the Head bolts torque and re-tighten as required.
You should now ride the bike keeping the revs below 4,000 if possible for around 25/50 miles and then re-check the head bolt torques.
You should check them again after a couple of hundred miles just to be safe.

HTH :)
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Re: Cylinder Head Removal/Coolant change

Postby 86bg » Thu Jan 13, 2011 6:34 am

Excellent resource you have here.

My question is about the o-ring that goes around the oil pressure regulator. I may have misplaced it and might have to order another. Can I use an o-ring from a replacement set? Can you tell me exactly how the little needle in there functions?
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Joined: Thu Jan 13, 2011 5:28 am

Re: Cylinder Head Removal/Coolant change

Postby Gman » Thu Jan 13, 2011 4:34 pm

I've used an O-ring out of one of these cheap O-ring packs before, ... 3cb1977fb1

They also come in useful for the O-rings on the Water pipes etc.Some will say they are supposed to be Viton©(Dupont) higher temp ones but when I had the heads off after around 8,000 miles the cheaper Butyl ones that were in these kits were in no worse state than the,"Official" ones".
The,"Oil Orifice" which is what it's called in the manuals and Partfiche is just a small pressure flow tube,It fits with the thin side/tube into the engine.It works by constricting the oil being pumped up there thus increasing it's pressure so it pumps better.
Whilst you have the heads off it's worth removing,cleaning and lubricating with molypaste ... 45f7f823a5

on the Rocker shafts taking note of position of the Spring curved thrust washers that secure the shafts when you pull the shafts out.
It's also worth dressing the tappets at this point for a quieter and better engine, ... essing.htm
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