12 replies to this topic

[087dave]

Hi all,

i have put a unleaded head on my 998 auto with a head gasket kit from mini spares

 

when i ran it up there was a metal to metal noise so i recheaked the tappets and they were ok

 

Then i ran it up again and the noise was there

 

so i took of the rocker cover and it dry not a drop of  oil, when i put oil on to it the noise went

 

so i am thinking is there a oil gallery blocked, i did put the head gasket on the correct way up

 

is there a difference on 998 heads could the gallery be blocked is there any check i could do???

 

Tks

 

 

[Cooperman]

You need to check that the oil feed hole to the rocker shaft is lined up with the oil feed hole in the rocker pillar. In fact the oil feed hole feeds a different rocker pillar on some heads, although I can't remember which heads this applies to.

Take the head off, blow through the oil-ways in head, rocker pillar and rocker shaft and see which rocker pillar has the feed to it.

I'm afraid you'll need another head gasket and maybe another manifold gasket too.

[087dave]

Can i ask how many oil gallery holes are on a head going to the rocker shaft

[sledgehammer]

The (cam4810) 998 unleaded head I have in the garage - number one tower feeds the rocker shaft (nearest stat housing)

 

number two tower is blocked - with the grub type screw thingy at the top & retainer washer , retaining the shaft

 

I have seen 998 head gaskets with one oil feed hole - so it is possible to have it the wrong way around

 

best of luck

 

 

 

 

 

 

 

 

 

 

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Edited by sledgehammer, 03 May 2013 - 07:07 PM.

[087dave]

Tks so its one oil feed hole from the head to the rocker post , and one hole for all the rocker posts

[sledgehammer]

rocker shaft (on the head I looked at)

 

is feed by number one rocker tower nearest the thermostat housing

 

It is a cam4810 998 head

[Cooperman]

There is just one oil feed hole in the head which takes the oil to the base of a rocker pillar. It then flows up the pillar and from there into the hollow rocker shaft. At each rocker bush there is a small hole in the shaft to allow the oil to feed the rocker bushes and from there just flow out onto the top of the head and then into the sump down the push rod holes, lubricating the cam followers on the way.

So if the rockers are not being fed properly the cam won't last long either!

[sledgehammer]

yep that one little hole does a lot of work

[087dave]

Thanks for that

[087dave]

Is there a difference of head gasket for a A series engine and A+ engine

 

because the unleaded head is from a A+      and the engine is a A series auto

 

Tks

[Cooperman]

The head gaskets for the 998 are all the same, but do get a decent quality one.

The difference between the heads could be the cause of the problem. Take the head off and line everything up, check the holes are all clear and that the head oil feed hole lines up with the rocker pillar. If necessary strip the rocker shaft and re-position the rocker pillars. Make sure the oil is feeding correctly and hope the cam and cam followers are OK.

[087dave]

Tks pete , the engine was only idling for about 15mins it wasnt under load or anything like that so should be fine as

i took off the rocker cover and put oil on from there and ran smooth

 

but does the cam and followers get oil before the rockers??

[Cooperman]

There is a lot of 'splash lubrication' from within the crankcase which feeds the cam, so don't worry too much. The oil running down from the head is just a bit more lubrication. The cam followers to cam contact is not pressure lubricated anyway. The cam bearings are pressure fed by the block oil-way system.

Try to find a lubrication diagram for an A-Series.