DEFENDER2.NET - View topic - 19J Experts help needed

↓ Advertise on Defender2 ↓

Home · FAQ · New Posts · My Posts · PMs · Search · Members · Map · Calendar · Profile · Donate · Register · Log In

Home > Technical > 19J Experts help needed

Page 3 of 3

Print this entire topic ·

Lodelaner

Member Since: 04 Feb 2010
Location: Lambourn
Posts: 621

1988 Defender 90 V8 Petrol ST Shire Blue

Hmmm. Being honest it all looks a bit overthought, based on assumptions and dodgy numbers.

Just some thumbnails: Combustion temps are around 2000 dC. EGT temp is around 700dC. Air rapidly compressed by .7 bar would reach less than 100dC, 21bar would be a 400 dC ish.

Is it thermal load that causes cracking, or is it the v shape that causes a crack to form in a weak spot due to combustion percussion? I have no idea!!

These engines (in later form) last pretty well if not thrashed and serviced properly. JB

@Lodelaner Instagram

Youtube greenlaning and other LR related content

24th Jan 2021 1:06am

Dinnu

Member Since: 24 Dec 2019
Location: Lija
Posts: 3197

2012 Defender 90 Puma 2.2 CSW Santorini Black

Hi Darren, indeed the calculations show a temperature increase that is well over the melting point of steel and aluminum (pistons). But as I remarked, these are theoretical numbers (isentropic compression) without thermal losses. In practice, as the air is being compressed by the pistons, there are heat losses to the pistons, cylinder bore and cylinder head as the compression takes time (however short it is). Then during the power stroke air is expanding, so it is cooling, although then heat is added by the fuel. Also to note that the calculation is at top dead center, so highest temperature is for very short moment.
As Jonathan said, the temperatures in real life are a lot less than the calculated values, due to the heat losses.
Indeed the later engines seem to cope better. The problem is that I cannot find what in the head is different between my earlier head and the later head that I acquired. I am not very sure what caused the original head to crack, but I believe it is caused by thermal stress. I think I have treated my engine very well in my ownership, regular oil changes every 5k miles, and the occasional coolant change too. I do not know however how it was treated in its first 6 years of life.
But could have been dodgy injections, poor fuel quality, and I think a lot of oil leaking from the valve stems. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black

24th Jan 2021 8:47am

Dinnu

Member Since: 24 Dec 2019
Location: Lija
Posts: 3197

Was looking over the cylinder head, as still waiting for the parts.
Noted difference in the hot plug design, worth mentioning.
Left is old head, right is new head.

Click image to enlarge

The difference in hot plug design can be seen in the deformation of the head.
Old head:

Click image to enlarge

New head (although on the new head I have already ran a stone to clean it up a bit).

Click image to enlarge 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black

8th Mar 2021 8:23pm

Dinnu

Member Since: 24 Dec 2019
Location: Lija
Posts: 3197

Have a question on the detail of the heat / swirl plugs as per my first picture in my last post.

That picture shows that the heat plugs have some material removed from the external side of the heat plug, rite on the side where the injector is firing.

I have ordered new aftermarket heatplugs, because the genuine ones are quite expensive, but these aftermarket ones, are just plain round, no material has been removed from the mentioned area.

Any one know why Landrover (or British Leyland) removed material there? My first assumption is to reduce heat transfer from the heat plug to the cylinder head. Is that correct? I am thinking that I should replicate that design on these aftermarket heat plugs, to be on the safe side. What you guys think? 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black

16th Mar 2021 8:03pm

Dinnu

Member Since: 24 Dec 2019
Location: Lija
Posts: 3197

Have been a bit idle.. but here is a short update on the above Hot /swirl / whatever plugs they are called.
As I have mentioned earlier, the aftermarket plugs are plain round. The original ones I removed from 2 different engines are of different design, but both have material removed from them, which I assume is for cooling or less heat transfer to the head.. not sure about the exact reason. So I thought I will go about and modify the aftermarket plugs to be closer to the later design original plugs.

Top view is not so clear, but I shaved 0.60mm close to the nozzle. I put the original plug next to the modified aftermarket one. I am sure readers can make up which is which.

Click image to enlarge

Click image to enlarge 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black

19th Aug 2021 4:53pm

Page 3 of 3

All times are GMT + 1 Hour

Jump to

< Previous Topic | Next Topic >

Posting Rules

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum