300tdi Discovery troubles

sam7986 · Oct 3, 2015

Hi guys just after a little advice, 6 months after changing the head gasket it's started to make a cha cha noise under load. To give a better description I've posted a video onto YouTube

The cylinder head was skimmed before replacement and I took great care in prepping the block and giving it a layer of wellseal.

The engine doesn't overheat but the temperature gauge fluctuates a lot and I turn off the engine as the noise only gets louder and does not sound healthy.

My thoughts are so far; either the block is warped in which case I'll just drop a new lump in, or the cylinder head is junk

It sounds to me that a lot of air is escaping meaning there's a sizeable gap somewhere

Any thoughts are appreciated

Cheers

Sam

jamesmartin · Oct 3, 2015

block wont have warped ,have you looked at the manifold gasket , also an over heated head is more likely to warp ,could be poor head bolts, check tappets and push rods

sam7986 · Oct 3, 2015

When the initial gasket blew I was mid on the way to London, by the time id realised it was overheating, I had driven a good 10-15 mins as my tracking was knocked off road so my steering wheel perfectly covers the temp gauge... Doh! Blew the rad and changed the head, all new gaskets all round inlet, exhaust, thermostat housing etc. Set the valve clearances and made sure it was all sweet.

Thought it would've been the head bolts being made of fudge so retightened them today and 2 were under 20nm...

How do I check the tappets?

Do I check the push rods via visual inspection?

Regards

jamesmartin · Oct 3, 2015

sam7986 said:
When the initial gasket blew I was mid on the way to London, by the time id realised it was overheating, I had driven a good 10-15 mins as my tracking was knocked off road so my steering wheel perfectly covers the temp gauge... Doh! Blew the rad and changed the head, all new gaskets all round inlet, exhaust, thermostat housing etc. Set the valve clearances and made sure it was all sweet.

Thought it would've been the head bolts being made of fudge so retightened them today and 2 were under 20nm...

How do I check the tappets?

Do I check the push rods via visual inspection?

Regards

theres a good chance head has bent
feeler gauge rule of 9
yes

sam7986 · Oct 3, 2015

This is a replacement cylinder head

jamesmartin · Oct 3, 2015

youd expect a new head to last longer but it seems either head or manifold gasket or valve issue

sam7986 · Oct 3, 2015

I will investigate further, appreciate the help mate hopefully I can resolve the issue without the need for another head

sam7986 · Oct 4, 2015

Just having a nose about in the bonnet today... the centre thread that holds down the rockers comes free with the nut suggesting the rockers are not being held down to the required torque, I also noticed that one of the inlet manifold bolts has disappeared but with doesn't leak or at least show up with leak detector spray...

My question I suppose is this, do I get a few timeserts threaded into the head and see if this resolves it? What's throwing me is the fact the heaters are ice cold and the coolant is pressurising suggesting the gasket has blown anyway, however the coolant isn't bubbling.

hoopfish · Oct 4, 2015

The coolant won't necessarily boil if the gasket has blown. Have you got white smoke?. Also when you torqued the head down how many nm did you do, also did you wind on a further 60 then 20 degrees?.

jamesmartin · Oct 4, 2015

sam7986 said:
Just having a nose about in the bonnet today... the centre thread that holds down the rockers comes free with the nut suggesting the rockers are not being held down to the required torque, I also noticed that one of the inlet manifold bolts has disappeared but with doesn't leak or at least show up with leak detector spray...

My question I suppose is this, do I get a few timeserts threaded into the head and see if this resolves it? What's throwing me is the fact the heaters are ice cold and the coolant is pressurising suggesting the gasket has blown anyway, however the coolant isn't bubbling.

heaters are cold when engines hot ?if gasket had blown from cylinder to water way ,coolant would erupt from the expansion tank ,though its common for gasses to pass over the gasket constantly pressurising the system, by how much depends on the leakage

300tdi Discovery troubles

sam7986

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jamesmartin

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