Cracked Heads and EGR

[That Ruddy Squirrel]

Hi,


Whilst having a butchers on the Aussie site I came across THIS which seems to imply that there may be a link between the dreaded head cracking and the use of the EGR

Anyone here had the head go when they have had the EGR disconnected for a while ? Could pulling the plug on the damn thing be a cure for this blight ?



Trev

[marky]

The HEADS crack due to very little amount of metal between the heads face & the waterways. EGR would not be applicable in this case, It happened at the wrong time for these folk as they still had the standard head fitted.
It was just time before it would have cracked anyway.

[That Ruddy Squirrel]

The HEADS crack due to very little amount of metal between the heads face & the waterways. EGR would not be applicable in this case, It happened at the wrong time for these folk as they still had the standard head fitted.
It was just time before it would have cracked anyway.

But if the EGR is causing the head to unevenly warm up, that would cause stress which could have an adverse effect on that thin bit of metal.

It's worth a thought


Trev

[iank01]

Excsue my ognorance but what is a EGR? Is this on the 3.0 l diesel also?

[That Ruddy Squirrel]

Excsue my ognorance but what is a EGR? Is this on the 3.0 l diesel also?

Yep you got one, it can be found by using search with keywords of EGR, smoke, & ball bearings.


Trev

[Dunno]

Yep you got one, it can be found by using search with keywords of EGR, smoke, & ball bearings.


Trev

Trev,

If I answer this poll is it tempting fate?????????

In which case can i hold YOU responsible

Paul

[Derek T M]

But if the EGR is causing the head to unevenly warm up, that would cause stress which could have an adverse effect on that thin bit of metal.

It's worth a thought


Trev

Yo Trev, the EGR only comes in when the engine is up tp full temprature so that should'nt count. However, I chickened out and reconnected mine, my train of thought being; small diameter exhuast = back pressure, more gas coming out = more back pressure = reduced performance...........?

I think I need a lie down.......................... ..


Derek

[Andy W]

Yep,
My old 2.4 head cracked a month after disconnecting the EGR, Could just be coincidence though,

Andy

[BUSHWHACKER]

Disconnected mine back in june last year, and so far no difference in engine temp
But then again, I am the second U.K. owner and I'm not sure if the head has been changed. Got a new radiator tho.

[pops]

Trev,

If I answer this poll is it tempting fate?????????

In which case can i hold YOU responsible

Paul

be a devil answer anyway

[kitesurf_phil]

I disconnected my EGR 20 months ago.

[Koi]

Yo Trev, the EGR only comes in when the engine is up tp full temprature so that should'nt count. However, I chickened out and reconnected mine, my train of thought being; small diameter exhuast = back pressure, more gas coming out = more back pressure = reduced performance...........?
I think I need a lie down.......................... ..
Derek

Not strictly true, on the vacuum type it works all the time, newer solonid ones are different. See below for a write up I did some time ago.

Exhaust Gas Recirculation Valve
Exhaust gas recirculation (EGR) systems were introduced in the early '70s to reduce an exhaust emission that was not being cleaned by the other smog controls. Oxides of nitrogen (NOx) are formed when temperatures in the combustion chamber get too hot. At 2500 degrees Fahrenheit or hotter, the nitrogen and oxygen in the combustion chamber can chemically combine to form nitrous oxides, which, when combined with hydrocarbons (HCs) and the presence of sunlight, produces an ugly haze in our skies known commonly as smog.

So basically it recirculates some of the exhaust gases back in to the block to reduce NOx. It says in doing this it reduces the operating temperature of the block, I have read many many articles on this topic. Some written by the Green/environment people who advocate you should never disconnect the EGR because of the detremental effects it has on your engine, of course they would, nothing to do with the environment of course.
Some by Profs. of motor mechanics, who don't deny in disconnecting the valve it raises the NOx levels released to atmosphere (our MOT laws in England don't test for NOx). They also claim that lowering the operating temperature is not a bad thing except the recirculated gases cause hot spots and on cast heads thats not good. The recirculated gases are reintroduced into the block on one side, so cooling that area not the far side of the engine, one side hotter than the other.
The other down side of the EGR is, in reintroducing the gases back in to the engine, this will place an even greater demand on engine oil performance through increased soot generation and acid levels. So you need to make sure regular oil changes are strictly adhered to.
The EGR also comes with another downside slight loss of power and decreased MPG.
The very early valves (like on the early surfs) were single diaphram valves that open on positve pressure (some open on negative pressure) these early valves entailed a mass of vacuum hoses within the engine bay. They were not that reliable, hoses can rot, split, the diaphram within the valve can perish, become perforated. All this leads to a non or poorly operational valve.
This system had many problems. It would often open to much, which caused a hesitation on acceleration as massive amounts of recirculated exhaust hit the combustion chamber. The peak temperature NOx is produced at only occurs when the engine is under full load, not all the time so with older style valves it recirculated all the time.
The newer valves are controlled by solonoids, so control the recirculation better only reintroducing the gases when the engine is under full load. So are more reliable don't effect performance so much or the MPG.
I have disconnected my EGR, I personally noticed more low down torque on my surf and better MPG. Yes my head has cracked 1 year after I got the motor and 10 months after disconnecting the EGR. Early heads had a design fault, the water ways being to near the valve guides. Newer redesigned heads have a thicker wall between the waterway and valve guide.
There are some who's heads have cracked and have never disconnected the EGR.
After replacing my head I reconnected the EGR for three weeks. Its diconnected again, couldn't stand the smoke it throws out the exhaust, the less grunt on acceleration and the worse MPG.
I hope this answers your question with an unbiased opinion, there are the greens who write articles on the EGR saying how great it is and mechanics who write articles saying the early valves were poor.
Thats the info, you make up your own mind.

[paul jones]

Egr

tried this mod to egr for approx 6months with no differance to performance so re conected pipe to EGR have owned my truck for nearly 4yrs now with no probs just treat it to reg service does the job for me

[BUSHWHACKER]

There was a real difference in performance when I disconnected mine, I can spin the inside rear wheel when pulling out of junction now, could'nt do that before.
p.s. and I have mud terrains fitted!

[Dunno]

be a devil answer anyway

OK DAD!!

Mine wont tick over with the egr connected, I disconnected it about 18 months ago, and it still runs as sweet as a nut with out it!

As to the head mine was replaced about 6 months before I bought it in April 2003.

Paul