Join Date: May 2003
Location: Houston, Texas
Feedback Score: 0 reviews
Re: EGR Cooler What does it do?
EGR (Exhaust Gas Recirculation) is a way of controlling/reducing the amount of oxides of nitrogen (NOx) emissions by effectively quenching the combustion temperature. It does this by introducing some oxygen-poor exhaust gas into the air intake stream. Less oxygen content means less burn means less burn temp which means less NOx formation.
That's a glossy explanation for a fairly complicated situation, but it covers the basics.
Now, on turbo diesels, controlling the inlet air charge temperature is important as it directly influences exhaust gas temperature -- and if EGT is too high, it can cause damage to expensive bits downstream -- such as the turbocharger. So to keep the EGR from spiking the inlet air charge temp (IACT) too high, the EGR gases pass through a cooler that knocks a bunch of heat out and transfers it to the coolant. This drops the EGR gas temp from as much as 1000F to 500F or lower.
That's a lot of heat, obviously. 900-1200 BTU/minute isn't unheard of. To give you an idea of how much heat that is, my home's heating furnace kicks out about 1250 BTU/minute, which is sufficient to heat a 900 sq. ft. house with minimal insulation (it's old [img]/ubbthreads/images/graemlins/smile.gif[/img]), even in Michigan winters.
There have been some issues with EGR coolers cracking along some of the brazed joints, which causes a leak. The later ones are less likely to have this happen, so your replacement cooler should last a good long while.
Hope this helps,
Former Cooling Guy
'99.5 F350 Lariat CC SRW 4x2, 7.3L 4R100
'99 Mustang Cobra, SCCA Solo2 E Street Prepared
'97 Dodge Neon, SCCA ITA/STU/EP Club Racing
Now I do subsea ROV tooling.