My initial thought on the EGR port in the intake manifold was to sleeve it with a PTFE (Teflon) sleeve thats 10mm O.D. X 8mm I.D. thinking there was no way Teflon would ever clog up again. After drilling my EGR port on my car, inserting a micro temp probe I'm finding that at times some of the heat in the EGR passage is exceeding the "sustained temperature" rating of the PTFE tubing.

PTFE will take sustained temperatues in the 500F range forever with no problems. But our passages are seeing intermittant temps spikes of over 750F. Most times the EGR passage is well under 200F but when the EGR dumps into the passage the temps go thru the roof. If this passage were more accessible or easier to get to when the intake is mounted on the car I'd risk trying it. But due to it's location and difficulty in keeping a close eye on I'm going to pass on the idea reluctantly in favor of a more prudent. less risky approach.

I have found that the EGR bore can be cleaned up very nicely to a mirror-like finish inside with 4-stage 10mm flex honing. The drawback is they are spendy @ about $13 ea for three plus one (120 grit) that's closer to $19 plus shipping. These actually cost more than many of my flex-hones that are 1-3" diameter.

Very easy to use the coarse (120 grit) flex-hone while submerged in the acid bath. Fast, aggressive, easy carbon removal. Then when out of the acid and rinsed off a progressive 180 grit, 240 grit, then a finish hone with a 320 grit, all using a little oil for lubrication. Looks like glass inside with no roughness for anything for the carbon, soot, oily vapors to stick or adhere to and start to coke/carbon-up. Probably turn this passage into a 500,000 mile maintenance procedure, if EVER, rather than the 60k-100k issue it is now.

Given that makes it a very expensive mod in and of itself. I'm going to recommend one other, far less expensive option which is to use a 3/8" or 1/2" bottle brush with a valve lapping compound. Both are easy to find at hardware stores (brush) and auto parts houses for the lapping compound. I've no doubt you'll never get the finish quality I've achieved but at less than $6 it may well cut this procedures needs by a factor of 2 or 3.

Just clean the passage after soaking in the acid for awhile with the bottle brush in an electric drill. Then remove and rinse thoroughly. After drying put some valve lapping compound and oil on the bottle brush, chuck it in an electric drill and spin at 1200-2000 RPM's while moving back & forth in the EGR passage. Then with dishwashing liquid on the brush clean and rinse out. Repeat as many times as necessary to remove all the surface roughness in the passage. Little more labor-intensive but a LOT cheaper. Pepeat the process in the outlet port in the throttle body flange where the passage enters the intake manifold.


Still wish I coulda made the Teflon work but this method should provide my never having to clean that port again even if I own the car for 10, 20 or even 30 more years (which I won't).