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Another 300tdi head gasket thread...


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Hi,

I rebuilt the engine in my 110 last year, including a new elring head gasket and bolts. The head was skimmed and pressure tested by a good machine shop.

I've done 5000 miles since, running well with good power. It has a boost pin and timing advance spacer fitted but the boost has not been turned up, it's done no towing, never been overheated, never lost a drop of water until last night. I was driving home, all running fine, not even up to temp yet when I noticed plumes of white smoke behind me. I pulled over immediately and it near immediately cut out. 

Opened the bonnet, it was spewing water out the header tank but it wasnt particularly hot water, thought I'd just see if it would fire up again but it wouldnt turn over.

So. I took the glow plugs out, turned the engine, number 3 and 4 full of coolant. I then took the head off, block and head both look ok but I've dropped the head with the engineer again for a check. The gasket had blown between 3 and 4 into the triangular coolant passageway. 

I am absolutely confident it was fitted properly, I've done more 300 heads than I care to remember but ive never known one go after 5000 miles. 

Has anyone got any suggestions for things I should check? I really don't want to be doing it again.

Thanks

Dave 

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If the head gasket went between 3 and 4 into the coolant passage ways that would explain both your white smoke and water pouring out because not only would it be letting water into the pistons causing the white smoke but pressurising the coolant system causing your spewing of water that wasn't hot.

As to why the gasket went in the first place the only reasons I can come up with so far are:

  1. Dodgy / damaged gasket
  2. Badly installed causing damage or the gasket to fail due to lack of clamping

So can't really comment on those options but to me it sounds like your failure was the head gasket first for whatever reason and the other symptoms were caused by it. Unlike mine recently which was overheating but hasn't damaged the head gasket.

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Thanks for the replies, the water pump was new at the same time as the last head gasket, so it's only 5000 miles old.  It's not shown any sign of overheating at all, the needle always sits in the middle, which is what makes the sudden failure of the gasket so surprising.

I carefully checked the gasket before fitting and it was torqued down with a snap on digital torque wrench.  The torque wrench also does the angle settings but i put a spot of paint on one of the points of the hex of the bolt and the head to check the accuracy too (each point on the bolt head should be 60 degrees apart).

I checked the block with a straight edge and the head was skimmed prior to fitting so must have been flat. 

Is it likely to be anything to do with having the boost pin fitted?  It's not particularly smokey, small amount of black smoke when accelerating up a hill but that's to be expected.  I only fitted it because the car has a 1.2 transfer box and as such is a bit too high geared.  I'm now thinking about removing the pin and trying to source a 1.4 transfer box.

Thanks

Dave

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Heater was working lovely, it was definitely circulating water, I'm confident it wasnt overheating but I do have concerns that perhaps the cylinder temp was too high with the boost pin fitted (I.e. cooling system coping but excess fuel causing high cylinder temp).

As an aside, would the timing spacer ring be an issue if it was left in without the boost pin? Most people seem to suggest the 2 go together but i did find a post suggesting small gains with standard fuelling, theoretically lowering egt.

 

Thanks

Dave

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Have you got a picture of the head gasket failure?

One of my (been through a couple of crankshafts a few years back) 300Tdis had the fueling wound up a lot and never had any issues with it. Given the coolant wasn't hot I'm struggling to see how the boost pins etc., caused any issues. Did you do the extra 20° required for the 10 main bolts? Having said all that the last four head gaskets I've done were just torqued up and then "judged" based off bolt angle rather than anything more precise and not had an issue with head gaskets.

It's not what you wanted to hear but based off the information to hand I think it's probably just bad luck with the gasket, the 300s are pretty resiliant engines unless you've overheated them which it doesn't sound like you've done. Assuming everything is flat like you say then I can't think of another reason. After the crank issues (failed crank pulley) my 300Tdi's run for 2 years with a 1.2 transfer box and wound up fueling with no issues and a fair chunk of that has been towing heavy loads across the country.

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I doubt it is anything to do with the pump mods.  It’s almost certainly an issue with a bad skim, bad gasket or installation error.  Did you use new head bolts?  They can be used up to five times, as memory serves.  Did you wick out the spilled oil and water from the head bolt holes in the block and tap the threads out?  Anything in those holes or threads could cause a bolt to bottom out.

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TBH it might have just been a weak gasket. 300tdi seem to need a periodic gasket change, they don't seem to last indefinitely, so there is probably no margin for anything not being absolutely bob-on. There is no doubt the boost pin would increase cylinder pressures (otherwise what is its point), but plenty of folk seem to run them without issue. I'd just check the flatness again and if Ok stick a new gasket in.

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Watching this with interest since I have almost exactly the same issue, albeit that the leak in mine is pressurising the coolant system and the engine still runs fine. 

What did you do about checking and selecting the right thickness gasket after you had the head skimmed?

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9 hours ago, nickwilliams said:

Watching this with interest since I have almost exactly the same issue, albeit that the leak in mine is pressurising the coolant system and the engine still runs fine. 

What did you do about checking and selecting the right thickness gasket after you had the head skimmed?

My understanding is that the gasket thickness does not need to be changed if only the head is skimmed - only needs to be changed if the block is skimmed.

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44 minutes ago, nickwilliams said:

And after a few hours work today, I think we have found the culprit, between No. 4 cylinder and the water gallery between pots 3 & 4:

Worth taking the effort to find out. Watching this thread with interest as about to fit a new gasket.

Simon...

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Just now, simonpelly said:

Watching this thread with interest as about to fit a new gasket.

What for a how to - just done one last night... :unsure:

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20 minutes ago, simonpelly said:

My understanding is that the gasket thickness does not need to be changed if only the head is skimmed - only needs to be changed if the block is skimmed.

Correct head gasket thickness is relevant to the highest piston protrusion. Tdi head gasket sizes.

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3 hours ago, nickwilliams said:

And after a few hours work today, I think we have found the culprit, between No. 4 cylinder and the water gallery between pots 3 & 4:

 

 

IMG_4247-r.jpg

Looks like the gasket was clamped down ok, might just be an errant bit of carbon or crud dropped when fitting the head, or a bad gasket?

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12 hours ago, western said:

Correct head gasket thickness is relevant to the highest piston protrusion. Tdi head gasket sizes.

The 300TDi overhaul manual actually says "If, however, cylinder head, pistons or crankshaft have been replaced, it will be necessary to check piston stand proud in order to determine the correct thickness of gasket."  but thinking about it, there is no reason why the stand proud figures would change if only the head is replaced. The book also says that heads should not be skimmed so I guess it's a case of 'guidance for the wise, obedience of fools'.

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52 minutes ago, nickwilliams said:

there is no reason why the stand proud figures would change if only the head is replaced.

Correct, however unless you have full knowledge of the engine, and that it hasn't had the bottom end rebuilt, it is possible that the piston height has changed from factory. 

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