300tdi - accidentally loosened 2 head bolts!

[SeriesKid]

I've been doing an engine swap this weekend, 300tdi for 300tdi for my defender.
I'm guessing my new engine came from a disco, as the fuel lift pump is different.

Anyway...
I'd spent about 20 hours over 2 days and was getting pretty tired (all the tricky bits were going well, but all the simple things we're proving to be headaches, such as the 2 hours I spent on the viscous fan nut, even though I had the spanner - had to make a pulley holding tool in the end).

After looking at trying to remove the air filter housing straps from the base plate (and the awkwardness of the bolts securing from underneath) I decided I'd just swap the base plates over. MISTAKE! Just plodding through, I couldn't understand why the bolts holding this on we're so tight... Then I realised what the hell I was doing!!!

I had loosened the two head bolts that secure the air filter housing base plate to the side of the head (the two on the drivers side at the back). After a quick look at the manual, I torqued them up to whatever it said, and then tightened them a further 60degrees each as instructed. It said to then do them a second 60degrees each, but as all the other bolts had remained at full torque, I just nipped them up about another 20degrees each.

Should I be worried??

[87County]

Well at this stage I would proceed and keep an close eye on coolant levels. At best you've caused no problems, at worst you'll have a head gasket to change - which will be a relatively simple maintenance job if the engine hasn't been overheated.

There are a lot of other variables obviously, you have given us no info on the engine's history.

don't worry too much - best of luck

[Blknight.aus]

I wouldn't panic, I've seen this a few times by people who've had to move the filter baracket to get access to the vac pump.

What I would be doing is replacing the head gasket and head bolts after you have it all bolted in and up while everything is still fresh. It will give you an indication of the condition of the engine the head and if the motor is not known to you or with a documented history it will give you another set of know start points.

It will also give you an indication and allow you to sort out all the little nigfly bits that often come to light only when your trying on a major repair on the side of the road and realise "damon it I can't get this bit off without a special bodge tool"

[Jode]

I've read that torque-to-yield bolts (your head bolts) are "torquable" 5 or 6 times before they fail. They are torqued at least once and possibly twice in the factory, then torqued when the head is installed. So another option would be to remove all of the head bolts and then replace them in their same spots, torqued in as per the WSM requirements, thus re-establishing the head's correct clamp pattern.

Doing this would however be a bit risky as you don't know if your bolts have been reused previously.

[87County]

I've read that torque-to-yield bolts (your head bolts) are "torquable" 5 or 6 times before they fail. They are torqued at least once and possibly twice in the factory, then torqued when the head is installed. So another option would be to remove all of the head bolts and then replace them in their same spots, torqued in as per the WSM requirements, thus re-establishing the head's correct clamp pattern.

Doing this would however be a bit risky as you don't know if your bolts have been reused previously.

If I was going this far I'd at least take the head off, clean it and the deck and replace the h/gasket and associated gaskets and consumeables.

As I posted , I'd try it "as is", but otherwise B'nites suggestion above in post #3 makes sense, it gives a starting point with the motor if you don't know its history.

[Blknight.aus]

Tdi head bolts may be used up to 5 times.

I personally will only use them three and won't reuse them if I suspect the cause of an.overheating failure was a long slow prolonged over heat or if I don't know how many times they might have been used before.


It's not that I can't use them 5 times it gives you a safety margin in the field. Pictmure.going out with head bolts that have been used five times and for whatever reason you have to pull the head off.. now alongside the gasket you also have to replace the bolts.

[SeriesKid]

Thanks for the replies.
Have you ever had issues with bolts stripping thread in the block?
I've had head bolts strip the thread inside an old p76 block before (alloy) and am terrified it might happen with this if i do end up replacing the head gasket.

[Jode]

The block is cast iron so should be good for the thread pull. But if previous repair guys were careless (didn't oil the threads/cap, used damaged head bolts, whatever) it's possible. But I've only done two head gasket jobs, and there were no issues there.

[Blknight.aus]

Thanks for the replies.
Have you ever had issues with bolts stripping thread in the block?
I've had head bolts strip the thread inside an old p76 block before (alloy) and am terrified it might happen with this if i do end up replacing the head gasket.

Yes, once, one of the narrow shank bolts ripped it's thread off of the bolt and left it in the block.

It wasn't a major issue as it came out and there was enough thread left at the top of the thread in the block to get a tap started to clean out the block thread.

But as has already been said it's a cast block with steel bolts, they're well protected and should have gone in oiled, the odds are in your favor that the worst that will happen will be Rounding the heads off .

[mudder110]

hi I did pretty much the same thing, I changed the head gasket on my300tdi.
at 220,000ks but forgot to put the air cleaner hosing bracket back on, m.r automotive advised me to just remove the two bolts replace the air cleaner housing and retention the bolts got 353,000 ks up now cheers .