Jump to content

300tdi head gasket


rocky
 Share

Recommended Posts

Hi, as mentioned previously, blown cylinder head. removed the head yesterday before i went to work. when i got home took the head to an engineering works to have it inspected. It needs skimming--fortunately it will skim without reseating the valves.

Two questions, are there any valve caps on a 300tdi, if there are then they are still on the head at the engineers (too much haste).

secondly on refitting the head can anybody confirm the angular torque tightening on the head bolts, stage 2--60deg, stage 3--120deg, stage 4--140deg on the

M12 x 140 bolts.

Regards, Rocky.

Link to comment
Share on other sites

Yes the 300Tdi should have valve caps, and they are cheap if you have to replace them. They tend to fall off and break into a ring anyway so maybe new ones are a good idea.

I think we are talking the same thing except you have cumulative angles....

1st stage hand tight

2nd stage 40Nm

3rd stage 60°

4th stage 60°

5th stage 20° on the inner M12 bolts only.

I find the trick is to mark the bolts with a line of tipp-ex or white paint. Then if you get confused in the middle of the job you can see which bolts have been turned, and how far. I don't bother with an angle gauge any more, just do it by eye.

Link to comment
Share on other sites

Thank Jim, Haven't used and angular gauge before.

Regards, Rocky

Rockey, I made one of hard cardboard, with 10º divisions, will post a photo later today, it worked fine, but will obviously deterioate over time, but how many heads do you plan to do, not three times in a row as I did, but again the angular guage survived 9 torque sessions. :rolleyes:

Link to comment
Share on other sites

Have been using the Tippex for years and it's a very reliable method - if you are interrupted while using an angle gauge you can lose track of which ones have been tightened .

With the Tippex a glance tells you which ones have been tightened . Make sure the bolt heads are clean so that the Tippex grips well and put all the marks at the same position .

The first 300 head I took off I lost some of the valve caps so I got 8 from the main dlr - and they were cheap , even here in the ROI.

Link to comment
Share on other sites

Have been using the Tippex for years and it's a very reliable method - if you are interrupted while using an angle gauge you can lose track of which ones have been tightened .

With the Tippex a glance tells you which ones have been tightened . Make sure the bolt heads are clean so that the Tippex grips well and put all the marks at the same position .

Dooroy, you are correct in that if one is busy with the torque sequence using the angle gauge, and you are interrupted, you will be trouble if you do not remember your last bolt torqued. I had a photostat of the page indicating the head bolts and drew a table, indicating the four stages, and the bolt numbers, ticked it off as I progressed, takes more time but I had to use my home made angle gauge <_<

Link to comment
Share on other sites

I first came across angle tightening many years ago on VW dsls and they had something like a total of 270 degs in 3 stages - following an initial 'settling torque' of about 35lbs. And for good measure they had another 90 after 500 mls .

It was the guy in the engineering works who suggested the Tippex and it worked well when the angles were 90 or 180 .

I always concentrated but on one occasion when a young cousin came to visit and fell as he ran in to say hello I was glad of the Tippex marks when I got back to the job.

When the angles are smaller the gauge gives good results . I have a basic gauge and have to get someone to hold it carefully while using it . I think you can get one with an arm which you can jam against some part of the engine . Even with the gauge I still use the Tippex - in case the gauge slips or the helper isn't concentrating etc . The 2 bolts at the back of the Disco head for example can be hard to use a gauge on .

Link to comment
Share on other sites

I have the angle guage that has a little arm on it that has to press against a part of the head in order to read the angle correctly. There are occasions when this type of guage just can't be used. I've had to convert angles to torque before now in order to tighten head bolts. I really don't see the benefit of angle tightening over torque tightening.

Les.

Link to comment
Share on other sites

I really don't see the benefit of angle tightening over torque tightening.

Les.

Angle tightening is more consistent and accurate in clamping force, Les. The clamping force exerted using a torque wrench depends a lot on the state of the threads, whether the threads are oiled, etc. Also many torque wrenches are woefully inaccurate as how many people have a torque setting gauge? In the Air Force they deliberately supplied us with torque wrenches that had no setting marks on them and were set using an Allen key and a torque gauge.

Also angle tightening can be used in cases where the torque required is greater than any torque wrench can be set to. I remember the torque of the nut that held the propellor on a Hercules engine - the nut was done up by hand using a big socket with bars on the sides, then the place was marked and the socket spanner bashed with a sledge hammer for a set distance, something like 1½". I think the torque would have been something like 1500lb ft.

Jim

Link to comment
Share on other sites

Would agree that angle tightening is much more accurate/consistent than torquing . In the case of the VW diesels some of the bolts would turn smoothly through 90 degs while others would be very stiff and jerky ( always new bolts and threads in head cleaned up ) .

Using a torque wrench in this case would have meant that while all would be torqued to the same value some would actually be much tighter than others . I have no idea of what torque would be needed to achieve the same tightness but the fact that you could have to go say 10 degs further when tighteneing in stage 3 as the bolt head would turn back that much when pressure was released would suggest a figure well above your average torque wrench .

I recall a friend in the trade telling me that many moons ago he had torqued the head on a Peugeot dsl as per instructions only to discover that the washer under one bolt was still able to turn . This wouldn't happen with angle tightening .

Link to comment
Share on other sites

When doing the VW's my procedure was ; make sure bolt holes were clear of oil/coolant ; then cut 3 slanted slots in one of the old head bolts at 120 deg intervals using a hacksaw and then use this as a tap to clean up the threads in the head - run it up and down once or twice ; then using new bolts apply the supplied grease to the bolt threads , between washer and head and between washer and bolt head . I felt this was doing the job properly .

Having gone through this procedure carefully proceed to tighten bolts ; some would turn through the appropriate angle so easily that at first I thought the threads had stripped ; others would take a bit more effort .

However when you got to the final stage you still had those which turned smoothly but there was usually one or two which required a lot more effort - to the point that you would think it wasn't going to turn and then it would turn .

If I was using a torque wrench those 1 or 2 bolts would probably have clicked having hardly moved very little if at all .

This would have meant uneven tightening and probably gasket failure soon again .

The torque would probably be fine if all components are new and in perfect condition .

A cylinder block with maybe 100K would be far from ideal and the angle tightening gives more consistent results .

When I used it first I thought it was time consuming / fiddly etc but I am convinced it gives better results when all components are not in the first flush of youth .

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy