L

lrjohn

Active Member
Notice today when I removed the filler cap from the coolant reservoir on my Td5 there was a little bit of pressure in the reservoir though the engine was stone cold and it hadn't been run for a couple of days. Is this normal or is it an indication, potentially, of a head gasket issue?
Anybody got any experience of this?

Thanks

John
 
If you heard a whoosh of air as the cap was removed it may well have been air rushing in as the air in the tank will have contracted as it cooled. Head gasket issues show when engine is running or just after it has stopped.
 
When you next use it and with engine proper hot, feel how hard the top hose is, watch fingers on fan!
 
Thanks for both the responses, I did wonder if it was air going in rather than coming out!

Lynall - how should the top hose feel when hot and what is this signify?
 
lrjohn said:
Thanks for both the responses, I did wonder if it was air going in rather than coming out!

Lynall - how should the top hose feel when hot and what is this signify?
Click to expand...

As Si says above, means head has possibly moved on the plastic dowels which then pressurises the coolant system.

But dont panic just yet, it could be just one of them things ie a one off.
I would check hose when hot and see if there are any minor leaks from coolant clips etc and see how it goes first.
 
lynall said:
As Si says above, means head has possibly moved on the plastic dowels which then pressurises the coolant system.

But dont panic just yet, it could be just one of them things ie a one off.
I would check hose when hot and see if there are any minor leaks from coolant clips etc and see how it goes first.
Click to expand...

Just asking to be sure, with the cylinder head bolts properly torqued to spec, can the cylinder head still move because it has a plastic dowel?

I had assumed that the dowels irrespective of the material they're made of, only serves to help install/locate the cylinder head and gasket in relation to block deck.
 
ifloochies said:
Just asking to be sure, with the cylinder head bolts properly torqued to spec, can the cylinder head still move because it has a plastic dowel?
I had assumed that the dowels irrespective of the material they're made of, only serves to help install/locate the cylinder head and gasket in relation to block deck.
Click to expand...

Opinion seems split. I too would have thought that the dowels were there to locate the head and that once the head bolts were torqued down, the head was going nowhere. Others claim that the evidence is that heads with plastic dowels do shift.
My 10p was professionally rebuilt before I bought it and the documentation shows that they used metal dowels.
 
ifloochies said:
Just asking to be sure, with the cylinder head bolts properly torqued to spec, can the cylinder head still move because it has a plastic dowel?

I had assumed that the dowels irrespective of the material they're made of, only serves to help install/locate the cylinder head and gasket in relation to block deck.
Click to expand...

Yes they can and do shift
My old td5 bought from a dealer and had to go back after a month or two did exactly this, they gave me the old dowels and they had shifted half the width of the dowel.
I have read of cases where it has shifted so much the valve has damaged the side of the cylinder bore!

15p engiens have steel dowels like engines of old, but can recall land rover saying you could not fit the steel dowels to the 10p block, but people were doing it anyway.

As i understand it , it all started with the k series petrol engines and the cylinder haad faces were getting damaged on the production lines, so someone had the bright idea of making the dowels out of plastic, how true this is I dont know but its sounds sort of believable, and we all know what an excellent rep the k series engine had:rolleyes:
 
lynall said:
Quick search
https://www.landyzone.co.uk/land-rover/plastic-dowels-in-td5-cylinder-head.48452/
https://www.landyzone.co.uk/land-rover/td5-head-worn-due-to-moving.173211/
https://www.landyzone.co.uk/land-rover/td5-metal-head-dowels.154118/
Click to expand...

An interesting read, thanks. This comment stood out:
"The rings that you have in your cylinder head sealing face are caused by the head bolts loosing there clamping load over time and allowing the multi layer cylinder head gasket to chatter causing it to bite into the alloy cylinder head."

So the head bolts effectively become loose. Does this imply that they lose tightening torque? If so is it worth checking head bolt torque on a 10p engine and would this provide reassurance that the head was not about to slip? My son's D90 is a 10p and unlike mine has not been rebuilt with steel dowels.
 
Si Click said:
An interesting read, thanks. This comment stood out:
"The rings that you have in your cylinder head sealing face are caused by the head bolts loosing there clamping load over time and allowing the multi layer cylinder head gasket to chatter causing it to bite into the alloy cylinder head."

So the head bolts effectively become loose. Does this imply that they lose tightening torque? If so is it worth checking head bolt torque on a 10p engine and would this provide reassurance that the head was not about to slip? My son's D90 is a 10p and unlike mine has not been rebuilt with steel dowels.
Click to expand...

Head bolts is whole other animal.
Basically they are stretch bolts and the inital low torque is just so they all have the same starting point, then all further angle tightening is to stretch the bolts ie the elastic stage, go to far or reuse the bolts to many times and they become plastic, plastic meaning they have no clamping force beyond how tight you do them.

Many moons ago engines did need their head bolts retorquing in service, this was pre stretch bolts

Head bolts are one fo the few bolts where I actually folllow the instructions!

I am not sure on td5 head bolts but some engines (Daf being 1 I know of) have sealant on the threads so once fitted they are fitted, retorquing could damage the sealant allowing coolant to escape/mix.
 
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