EGR valve

[cuz 62]

after reading all the comments on the EGR mod thought i would give it a go this evening just got back from a test drive what a difference pulls away a lot better wish i had done it before

[firefly]

Cuz i am thinking of doing it just a bit worried about the extra heat build up when engine is under load especially when i tow a caravan with mine, dont wanna cook the engine

[NorthWestDirt]

Cuz i am thinking of doing it just a bit worried about the extra heat build up when engine is under load especially when i tow a caravan with mine, dont wanna cook the engine

Not sure if I've got this wrong, but I understood that disconnecting the EGR meant an increase in Nitrous Oxide levels and thus, a reduction in engine temps?

Can someone confirm my (mis?)understanding?

[Koi]

Not sure if I've got this wrong, but I understood that disconnecting the EGR meant an increase in Nitrous Oxide levels and thus, a reduction in engine temps?

Can someone confirm my (mis?)understanding?

Its swings and roundabouts, Nox is only produced over 2500 degrees which is higher than than the normal running temp of the engine. Under load i.e long uphills, towing puts the temp over 2500 deg thus producing Nox. Under load needs to be as it says, towing on the flat doesn't always mean the engine is under load as once its moving its not under real load.
The EGR reintroduces the exhaust gases back into the head because they are cooler than the running temp of the head thus preventing temp getting over 2500 deg.
See this write up from one of my earlier posts.

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.
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.

[Guest]

Just to add to Koi's excellent description, the reason that EGR reduces the running temperature is because the Exhaust gases reintroduced are inert and don't burn. This reduces the burn efficiency of the engine and therefore the running temperature. However that is why you feel an increase in performance when you remove the EGR, because the engine can now run at higher efficiency.

That is also why you get less smoke out the back, black smoke is unburnt fuel, low burn efficiency means unburnt fuel, better efficiency means less unburnt fuel. You should also see better fuel economy because you are now using more of the fuel and throwing less off it out the back unburnt. You will go further with less fuel and also not have to drive around with the throttle nailed to the floor all the time.

In theory head temp will increase however one of the downsides of early EGR systems is that the reintroduction of the exhaust gases can cause localised hot and cold spots which is worse for the head than an overall high temperature because it can set up localised stress points leading to failure.

Plus, remember the 2L engine was designed long before EGR was invented. More modern diesel engines were designed after EGR and are therfore fully tested with EGR before being put on the road.

Thats my twopenny worth anyhow.

Cheers

[firefly]

hmmmmmmmmmmmmmmm very very interesting. right im going to have a go at it and see if it makes any difference, am i right in saying its the goldish coloured cyilinder shaped thing next to the fuel filter and all i have to do is disconnect the pipe and block the pipe and the fitting on the egr inlet...hope thats easy enough to understand

[Koi]

hmmmmmmmmmmmmmmm very very interesting. right im going to have a go at it and see if it makes any difference, am i right in saying its the goldish coloured cyilinder shaped thing next to the fuel filter and all i have to do is disconnect the pipe and block the pipe and the fitting on the egr inlet...hope thats easy enough to understand

No, just block the pipe (one with the plastic valve type thing on it) leave the EGR alone.

[computingfuture]

No, just block the pipe (one with the plastic valve type thing on it) leave the EGR alone.

intructions please. how do I block it?

[Koi]

intructions please. how do I block it?

pull of rubber hose to the EGR and stick a bolt, ball bearing basically anything that will block the pipe up.
Oh sticky back plastic don't work

[stimpy30]

h,mm

hi ive got a 2.4 auto just read your thred and now i,m totaly confused was toying with idea of pulling of egr but i work on various vehicles had a couple of merc diesals come in recently with low acceleration and poor fuel mph this was due to egr failure which is opposite of surf results in,t that weird asked me mate at merc tech and he said egr failure on merc is deffo power loss wonder how come they work opposite

[marky]

Because the japs are cleverer than the germans LOL

[Koi]

hi ive got a 2.4 auto just read your thred and now i,m totaly confused was toying with idea of pulling of egr but i work on various vehicles had a couple of merc diesals come in recently with low acceleration and poor fuel mph this was due to egr failure which is opposite of surf results in,t that weird asked me mate at merc tech and he said egr failure on merc is deffo power loss wonder how come they work opposite

Depends if it failed close or open, if they fail close you notice no difference. If it fails open then poor acceleration, hesitation on acceleration, lumpy tickover and loss of mpg.
On newer models the valve is different in that its normally a solonoid type, on the older surfs it was a diaphram type.
Newer models also work different that they only open on full load when more heat is generated, not more or less all the time like the early ones on surfs.

[firefly]

Koi mine i think is a selonid type????? its a L reg 1994 ish i am completely usless at anything mechanical so i really am at a a loss i will endevor to take a pic and post it to see what you think if thats ok b4 i take the plunge