How to compression test a 300tdi

Hi Gerry, "Life is but a dream .......... shaboom, shaboom.....", can't really say we're both surprised. I'd be a bit loathe to get the original head machined as the factory heads are absolute crap from a metallurgical perspective. Get a hardness test done if you reckon it's worth saving, but otherwise junk it and go for a 'OEM' replacement. Roverlord will look after you for bits but Turners for example(in the UK) is the place to go for a new head. ****ing computer....................can't insert a space...................will try again. :angry: :o Deano :(

Quote:

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Originally Posted by wedgetail37

:):)Good morning Deano.

" There's only two or three bolts that hold the manifold on with the front and rear bolts fitting into 'slots' in the manifold. These are the same bolts that hold the heater pipe mountings."

Thats the problem above. One of those bolts are already round and I cannot remove the inlet manifold. Thats why I had to disconnect the exhaust flange. It is a real nuisance, but I hope when I get the whole lot out I will be able to somehow remove the bolt.:censored:

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Which one is rounded one of the short ones that bolt through and hold th manifold or one of longer ones a the bottom thats slotted?

Another point to consider if shaving the head is the valve to piston clearance.


Say for example you shave 10 thou (0.25mm) this will decrease the piston to valve clearance on no.1 and 4 by nearly this amount, say 8 thou. As the head gaskets come in 4 thou (0.1mm) increments I would assume that this 8 thou is significant. It may be necessary to grind the valves/valve seats to restore the correct clearance. :confused: Using a thicker gasket may compensate for no1 and 4 but the gap on no2 and 3 would then be bigger than it should be resulting in lower compression on these two cylinders.


I don't know for sure if this is a real issue or I'm reading too much into it perhaps Dave or someone who knows would like to comment.


Deano :)

Not worth worrying about,

stick the fattest gasket in and dont worry about it.

that said.

check the piston protrusion on the deck and the deck for level......

:):)Hi Blknight.aus
Thank you for your advice, but I got lucky once i had the whole lot out in one piece. My son belted a 3/8 ringy on the 10mil and that did the trick. It was a long one that didnt have the slotted bracket. Have a good night/day. The guy at the engineering said it was quite bent and he shaved quite a bit off. I hope I have done the right thing and put a gasket with 3 holes in the tab back on the motor. I did the first 29lb torque in the right sequence and have yet to do the 60 degrees without a special torque wrench with degrees. I have made a cardboard Jigger with 60 and 20 degrees marked. It would be easier if it was all lbs/ft and not the 60 degrees x 2 and some bolts another 20 degrees x1. See ya - Gerry:D:D

:):)Hi Deano, see comments above to Blknight for an update. I got all the gaskets, thermostat, expansion tank cap etc from Roverlord. Also I ordered a Timing Belt kit that should be here Monday/Tuesday. I thought it a good idea that I do this as well whilst I already have a lot of the bits out of the way. Tried to find a cheap Harmonic Balancer Puller on ebay but could only find one that fitted the ones with 3 holes. I will keep looking. I have the head back with a shave and new valve stem seals as it blew smoke on startup. The valves and seats were excellent. Have a beaut night/day mate and a good weekend. See ya - Gerry:):)

Ps, only $285 for the head work which included $90 for new head bolts.
Pps. Got my Laptop back from warranty. Much easier than the Mobile or Tablet

Bent? and shaved quite a bit off?

time to stop...

you need to check the level on the rocker shaft pads and make sure the head maintained hardness.

the first will cause presature wear on your rocker arm bushes, may crack the rocker shaft and can give you issues with an increased wear rate on the cups on the valves

If the head doesnt pass hardness your in for an early failure.

heres a couple of primers for you.

http://www.aulro.com/afvb/projects-t...ming-belt.html

http://www.aulro.com/afvb/projects-t...op-basics.html

:):)Good morning Deano and Dave.
I have learned an awful lot from you guys. Also I should have listened more before I leaped. I will buy a straight edge today and check the rocker pads to straightness. I have the shaved head on the block tensioned to the first level 29 ft/lbs. Will this be ok to check the level of the rocker pads.
Where exactly do I place the straight edge to do the measurement and what would be an allowed tolerance?
Also, would you guys think I would be better just taking the head off the spare 1994 D1 I bought to ravage parts off. As far as I know it has no overheating problems.

I thought all was well with my cheaply shaved head and new valve stem stem seals and was patting myself on the back until I read the posts from you guys. That deflated my ego pretty damn quick:( hahahahaha.

3 more questions if you dont mind.
Can I reuse the head gasket?
Can I reuse the head bolts?
(Both have been tensioned down to 29 ft/lb)
How do i test the hardness of the head?

I thank you both again and all members involved in this post. Have a beaut weekend. See ya - Gerry:D:D

Hi Gerry, How much was 'quite a bit' ? Daves got a good point about the rocker mount pads, though they can presumably be shimmed or ground (same as the other side) to make them all the same height.


Don't worry too much about the convoluted bull**** in the workshop manual regarding how to tighten the head bolts. Who but the bloody pomms would come up with 60 + 60 + 20. :wasntme: :( in the first place :confused:.
A MUCH simpler way is to use the bolt heads as your guide, each bolt head flat is 60 degrees apart.
I do it this way


1/. clean the head of all oil etc.
2/.well oil the bolt threads and do them up to the specified torque
3/.get a pointy auto type marker pen and put a small dot on the corner of the bolt heads where two flats join and another dot on the head directly under it.


60 degrees is now 'one flat' of the head and easy to obtain and the final 20 degrees is 1/3 of a flat but make sure this is on the thicker bolts only.


Another benefit of doing it this way is that if you lose count you have a visual indication of which bolts are done up to what. :D
Something like this


https://www.aulro.com/afvb/images/im...2015/02/34.jpg


As for needing a puller, you may not need one. I've done three and perhaps I'm just lucky :) but I haven't needed one yet.




Deano :)

Hi again Gerry, Don't give up yet. :D


Knowing how much did the bloke machined off would make it a bit easier to decide which way to go here.


But you can use the rocker shaft and its pedestals as your straight edge to measure between the pedestal base and head (pad) using feeler gauges. :)Internal webbing in the head (from memory) will prevent a straight edge from fitting directly across the pads. Shim steel in various thicknesses can be bought quite cheaply from an engineering outlet to 'pack the gap'. And this problem will be solved.


NOTE. Grinding the pedestals is a sin and you'll go straight to hell !! :o :wasntme:


How much has been shaved from the head will determine whether you can use the three hole head gasket, not that it's been done up to 40 Nm, but the thickest no hole one is only 0.1mm (4 thou) thicker. If, as you say, a fair bit has been machined off I'd take a close look at the 'Valve Head Stand Down', page 26 in the overhaul manual link I posted earlier and machine the valve/seats accordingly. Again, it all depends how much needs to be taken off which is determined by how much has come off the head. :)


Yes you can re use the new head bolts as the 40 Nm they have been tightened to is neither here nor there in the scheme of things. :D


The bloke who did your head machining should be able to steer you in the right direction re hardness testing services in your area.


I don't know if I'd give up on the old head yet unless its been machined so much that valves hitting pistons is a problem :o. I'd probably go with "better the devil I know", shim the rocker pedestals and give it a go.


If it turns out that the head is too soft and the gasket/head fails again and with your new found knowledge swapping the head over will be a piece of **** :D:D. Just make sure your spare is a 300 tdi and not a 200 tdi.


Deano :)