300tdi Rebuild

[edwardbahaw]

Hi Guys

I have removed the cylinder head from my 300tdi in preparation for an engine rebuild.

The cylinder liners are wore about 1 mm.

Putting cost aside, what is the best option for this rebuild?

Bigger pistons or replace liners?

Regards

Ed

[sheltie50]

Just to throw a spanner in the works--

Might save you a lot of bother just to find another engine.

[Range Rover Blues]

Are they lined? I have to say that either way sounds expensive. I'd go for bigger pistons = more cubes.

[edwardbahaw]

Are they lined? I have to say that either way sounds expensive. I'd go for bigger pistons = more cubes.

Anyone out there who would second this!

Are there any complications that can arise from re-boring and using bigger pistons?

I take it that if the cc increase then I may have to increase fuel pressure and boost.

Anyone with experience on this?

Regards

Ed

[edwardbahaw]

Also, not bragging here or anything ... but cost is not really a problem!

I think because where I'm from labour is quite cheap!

Plus I have been saving for this project for over 2 years!

[dooroy]

Last year I had to fit a new head to a 98 300 Tdi - had about 130K on the clock .

I decided at the time to fit new rings as well - just honed the cylinders .

I don't think any 300 Tdi's had liners - but could be wrong .

All the work could be done with engine in place and results very satisfactory .

I didn't measure the amount of wear so can't comment on that.

[Phil B]

Drop in a 2.8 tgv

[matt bristol]

1mm wear I assume means a step in the top of the bore of 0.5mm or so, which in engineering terms (I know its a Land Rover) is big enough to drive a wagon and horses through.

More cc = more power is one arguement, but seriously, on a Land Rover TDi? better to have it running properly and within tolerance than chase the elusive extra 2mph 'more' power could give you. I would suggest either rebore or replacement block and pistons, mine hhad hardly any bore wear when i took the head off (certainly a lot less than 1mm) but it still chugs like a steam train at times and still pulls like a train all the time.

[edwardbahaw]

The cylinder liners are wore about 1 mm.

Guys

I realized I made an error on my initial post!

I really meant to say about 1/4mm wear on the liners.

Thanks for your suggestion Newbie

I still have to take it to the machine shop.

I'm thinking that re-boring and using +10 thou pistons might be appropriate for this level of wear.

... chugs like a steam train at times ...

This is exactly the symptoms I had before I removed the head ... and is what I want to remedy

Regards

Edward

[JimAttrill]

In my garage I have all the bits to recon my 300tdi when it needs it. It now has 290 000 kms (about 181 000 miles) on it and refuses to give up

But the bits I have include 4 standard Kolbensmidt pistons and 4 liners. Oversize OEM (KS) pistons are very expensive, so it normally works out cheaper to buy liners and std pistons instead and have them fitted and bored to size. It all depends on what your local engineering shops charge for this. Here the liners work out cheaper. I think the liners came from Britpart.

[edwardbahaw]

Here the liners work out cheaper. I think the liners came from Britpart.

Just curious are the liners wet or dry?

[JimAttrill]

Dry. The engineers bore the block out, press them in and then bore them to size. You can also get them for TD5s for which o/s pistons were not available. They may be by now of course.

ps the 300tdi liners can be used on all 2.5 engines of the same bore, petrol and diesel.

[edwardbahaw]

Hi Guys

Just sending an update!

I had the block bored and the new liners pressed in.

The guy at the machine shop said he skimmed 3 thou from on top of the block.

Will this cause any problems such as the pistons hitting the valves?

Regards

Ed

[edwardbahaw]

Will skimming the block 3 thou from on top cause any problems such as the pistons hitting the valves?

Anyone?

[JimAttrill]

3 thou is negligible. However, you MUST measure the distance the pistons are above the block at TDC. There are laid-down limits for this if you RTFM. This should be done in any case to figure out which of the three gaskets to use. If the pistons stick up too much (I don't think you will have to worry after .003") you will have to have the tops of the pistons skimmed to get it right. Engineering shops know all about this they do it all the time to big truck diesels.

[edwardbahaw]

Thanks so much Jim!

The guy at the machine shop have worked on a couple of 300 tdis in the past and he said that he has done this before (3 thou skimmed from the block)

I was checking here in the forum to make sure he was not bull****ting me!

I also did some research as well.

The one hole head gasket is 1.37mm

The two hole head gasket is 1.48mm or 4 thousand of an inch thicker than the 1 hole

The three hole head gasket is 1.48mm or 9 thousand of an inch thicker than the 1 hole

Of course when the head bolts are torqued, this will compress it bit ... at least I think so!

I'm thinking that the 3 hole should be appropriate.

When the crankshaft and pistons are refitted I will see how far up the pistons come up on top of the block.

I will also check to see if the head gasket would provide sufficient space to avoid the pistons from hitting the cylinder head or valves.

[edwardbahaw]

Thanks so much Jim!

The guy at the machine shop have worked on a couple of 300 tdis in the past and he said that he has done this before (3 thou skimmed from the block)

I was checking here in the forum to make sure he was not bull****ting me!

I also did some research as well.

The one hole head gasket is 1.37mm

The two hole head gasket is 1.48mm or 4 thousand of an inch thicker than the 1 hole

The three hole head gasket is 1.48mm or 9 thousand of an inch thicker than the 1 hole

Of course when the head bolts are torqued, this will compress it bit ... at least I think so!

I'm thinking that the 3 hole should be appropriate.

When the crankshaft and pistons are refitted I will see how far up the pistons come up on top of the block.

I will also check to see if the head gasket would provide sufficient space to avoid the pistons from hitting the cylinder head or valves.

[JimAttrill]

Of course, when they fit liners they leave them sticking out a bit and then the top of the block has to be skimmed slightly otherwise the gasket will instantly blow. It's a good idea to measure the piston protrusion for it will also tell you if you have a bent con-rod. If you do have a bent rod, that piston will not protrude above the top of the block. You don't absolutely need a magnetic stand and a DTI, you can use a steel rule and feeler gauges.

[edwardbahaw]

You don't absolutely need a magnetic stand and a DTI, you can use a steel rule and feeler gauges.

I will most definitely use this technique to measure the protrusion

Thanks Jim

[edwardbahaw]

Guys

I need some advice about this, AGAIN!

We're finally at the re-assembly stage and noticed that when we fit the new ring (top compression ring) about halfway down the bore, there is a clearance of about 15 to 20 thousandth of inch at the gap (where the two ends of the ring meet.

Can such a clearance be tolerated, or would it loose compression?

Regards

Ed

[JimAttrill]

Edward, pm me with your email address and I'll send you the LR 300Tdi overhaul manual from home tonight. It is 104 pages (or 52 if you print it double-sided) 2Mb PDF. It will answer all the questions you need.

[edwardbahaw]

This is a video of the block with the pistons re-fitted.

Even though standard pistons fitted and bore re-lined to standard specs, the pistons can still move in the bores!

Would this lead to problems?

These are the specs

• The bore diameter is 90.47mm
  
• The piston diameter is 90.395mm
  
• The ring gap clearance is 0.4mm