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Err, clean the piston crowns? That's something I was taught never to do. My taxpayer funded skillset doesn't equal yours, and has been dormant for a couple of decades, but I'm struggling with that one. Too much risk of hard carbon falling down into the bores, they said ??Quote:
Originally Posted by Blknight.aus
This is going to be a slow and methodical rebuild, because I don't want to do it again. I'm too old for that. I'll take your advice and check all that stuff before the head is done. What do you say about skimming the head? RAVE says no, but I reckon modern head shops can deal with hardness issues.Quote:
Originally Posted by Blknight.aus
you can clean the worst of the carbon off but its not essential ( I TDC the piston, stuff some string down the sides, use a wet and dry vac and go gently with a toothbrush.) but what you're really after is cleaning the block so you can straight edge it.
the head can be machined but only so much and it needs to be hardness checked before and after machining along with making sure the rocker shaft posts are level.
The odds are that if you're doing this as a preventative maintenance job it doesnt need any machining it just wants a bloody good clean, a check over and a new gasket with some new bolts.
unfortunately the tdi heads is one of those beasts, its very easy to miss a simple check early on in the piece and turn it into a money hole.
Money hole... Where have I heard that before?? Once uponna not long after I left the Army, with the incomplete training that was the norm for the "we have to get out of Vietnam at any cost" days, I spent some time working on BMW and FIAT cars. Boy. It's why I rely on this forum, and people like you.Quote:
Originally Posted by Blknight.aus
Am I likely to find issues with the block facing ( cast iron would suggest not in my experience )
? At this early stage I can detect no particular movement of the pistons, and there is no piston ridge. In fact, I can still see cross hatching marks in the bores. If there wasn't so much negative talk about these engines I would simply have the head checked and then chuck it back together ( Yeah Dave, clean and all. BWW's like that too).
It's not rocket science surely. Or is it? People fixed these things in paddocks, didn't they?
Usually the block only goes after its been abused or some drops something on the face of it. BUT...
-.003 right between #2+#3 on the block and -.003 in the same place on the head makes up for -.006 variation between deck and head with a tolerance of +/-.005 so its definately time for machining the head or a new head.
The most important part of the pistons to check is the bore condition at about the 1/3-2/3 stroke postion you're looking for an elongated oval on the thrust side of the piston, any early bore damage is most likely to show up around there as its when the piston usually has the highest pressures on it and the highest velocity. as far as protrusion goes, you're only looking for any oddity in the motion of the piston as the crank turns past TDC for 1+4 +2+3. if you really want to check the crowns (and I usually dont unless Im getting the run on bad oil and overheated and overfueled and abused) what you're looking for on the crowns is a kind of crystallizing of the ally in the combustion chamber its really hard to describe accurately but imagine looking at a polished matt finish when you should be looking at natural gloss.
But if you werent overheating, burning coolant or leaning the pressure on the cooling system I'd go so far as to say you probably wont even need the head machining.
its not quite rocket surgery but its getting on for brain science...
and yes, I've reheaded a couple in paddock conditions. IME its less about where you do it its about your prep work and attention to detail when you do it.
hows that saying go, measure with a micrometer, mark it with chalk and then cut it with an axe. no, not thatone.. ummm
we dont have the time or the money to do it right the first time but we can always find extra to re do it.
nahhh, how about...
qualities good, and quantity is nice but a quantity of quality is hard to beat. or
Properly, Quickly, Cheaply. Choose 2.
they sound nearer the marque.
John, if you do get the head surface skimmed, talk to your machinist about recessing the valves a bit deeper into the head to maintain clearance (depending on how much metal is removed of course).Quote:
Originally Posted by johntins
My experience with laminated metal gaskets (esp. Victor Rienze brand) has been good, there are a few posts in the forum re: this subject.
I believe that the 300TDi alloy head is inherently flawed and seems to warp between #2 & #3 cylinders.
First time I blew a head gasket I had the warp machined out and valves recessed, I used an Elring comp. gasket and shortly after the gasket blew again, as I had to repair on the side of the road and the warp in the head was back, I used another Elring gasket, which lasted about the same amount of time.
The Head was in poorer condition and the warp was worse than before, as I was in Canberra I consulted the owner of Canberra Motor Works, he advised that VR Laminated gaskets were the best available and should last till I could afford to buy a new head.
Contrary to what a certain Guru on all things on here claim, mainly that laminated gaskets are not suitable for anything other than a NEW head.
Well that Victor Rienze laminated gasket lasted several years before I bought a new head and was still good when I replaced the old head with a new head bought here in Australia.
A laminated gasket for the 300TDi is now standard upgrade for LR 300TDi from LR, so I recommend the MLS type gasket, but get on Google and U-Tube and check it out for yourself, good luck, Regards Frank.
As Dave said, the only block issues I know of other than core shift, which can happen with any manufacturer, is a mate had his deck drop in the middle after the block had been decked, the engine rebuilt and run for a few thousand km.
That engine had a runaway prior to it's rebuild.
This engine had one overheat, When it climbed when stopped for maybe 20 mins, so the temp alert sounded as soon as I started it. It climbed to 110, but came back down when I turned on the aircon. There is no A/C belt fitted, I turned it on to switch on the fans. It came back don to about 84. The next day it climbed to the mid 90s, when before it would never get above 82 unless on a long highway drive, which I blame on that dirt clogged radiator.
So, I decided to pull the head before too much damage could be done. The car has always lacked power, so it's a good time to investigate that, and also to do the timing belt that has been sitting here for months.
What I've seen so far with just a cursory look is that it all seems to be in good nick. When I get home later in the week I'll be looking deeper, but for now I'm hopeful.
I'll get the head checked, but I won't skim it unless it needs it. I wonder what gasket the head guy will recommend. :wacko:
Thanks for all the advice.
http://www.aulro.com/afvb/discovery-...nder-head.html
theres another head replacement build for your perusal.
Just a word of caution about an old timer on this site, he likes to omit and rephrase things and represent his opinion as fact to suit his end needs,
sounds like youre doing a precautionary to me, so long as you dont skimp on it or take short cuts its going to come up apples for you.
if the timing belts old and stretched the injection will have been running late, same for the valves but not by so much.
It might have also suffered a hole inthe boost diaphragm or not been tuned up right to start with.
Theres a whole bunch of things that can cause low power dont forget to check the exhaust, I've been caught out by a dud muffler and collapsed/crushed pipe more than once.
I wouldn't sweat 110*, seen that more times than I'd care to admit and it's within Land Rovers engine temp limits for the Tdi, even if it's scary seeing it there.Quote:
Originally Posted by johntins