EGR and bypassing EGR spacer coolant... debate

No, removing the EGR will not help performance. The only "advantage" to removing it would be to clean up the engine bay a little, and removing something that can break. That is why I removed mine, the sensor went bad and was causing a "bucking" issue at cruising speed. Instead of replacing it, I simply disconnected the vac line to it. Now that I have the TwEECer, I disabled the EGR (and Thermactor) from the PCM. Now I can physically remove the EGR valve, sensor, and all corresponding vac lines, ect. It helps me clean up the engien bay a little, and I removed things that can break.

I am going to be doing a head swap shortly, and I will block off the EGR passage in the head as well.

None of which is going to give me ANY performance gains. I am simply doing it to get rid of stuff I really don't need. Such as sensors that can fail an d cause driveability issues, and vac lines that can leak.

If you have no need for removing the EGR, then I would leave it alone.

Oh, as far as the coolant lines go....I never put them on when I assembled my engine. I have read the arguments for both leaving them and removing them. Neither side ever actually has any facts, it is all theory. According to Ford it was designed to HEAT the EGR passage. Me personally, I didn't hook up the lines because I knew I would be deleting the EGR anyway, so no hot gasses pass into the spacer.

I never run them

Unless you have blocked off the egr passages or eliminated the egr entirely run the coolant lines. I now have my passages blocked and egr is gone. But, I learned the hard way back in the day, I tried this and the gaskets between egr spacer and the tb spacer cooked themselves into submission! Extremely hot gases passing through there.

IF the coolant didn't serve a purpose, Ford would not have bothered routing it to the EGR.

It is there to cool the EGR gasses.

If you remove the EGR, then it is best to plug the egr passages at the heads.

If you unplug the egr valve, it is disabled in the computer. The 'alternate' strategy the computer uses when the egr seems to disapear, will work the same as turning off the egr function with the tweecer. In theory anyway.


I wish I still had my egr setup.
I removed it when doing the 351w conversion, and never figured out how to get it back in there.



jason

As stated, I don't think anybody's definitively proved one way or the other that bypassing the EGR spacer's coolant lines has a positive or negative effect. The way I see it, if I plan on adding a phenolic spacer so the upper intake doesn't soak up heat from the rest of the motor and, thus, gives the incoming air that much more travel distance/time without exposure to serious heat before it gets crammed through the lower manifold and into the heads - leaving the EGR spacer hooked up to antifreeze flowing through there at about 200* would be completely counter-productive. Many folks have bypassed their EGR spacers' coolant lines without any ill effects, including myself.

Not to call you a liar or discredit your claim, conv91lx, but I find it hard to believe that extreme heat from the EGR, itself, was what caused your gaskets to fail; if they were the originals, then it was probably just general age; if they were new ones, perhaps they didn't get set in right during the re-install, they were improperly torqued, or they were just cheap-o gaskets (even the FelPro ones look as flimsy as the ROL brand ones, like super-thin cardboard). At any rate, there's lots of other gaskets throughout the motor of the same material that are exposed to equal or greater temps, yet they seem to hold up over time just fine.

Been running mine without coolant lines attached for over a year, no prob's. Kinda had to delete mine, anyways, because my heater pipe was rotting/leaking and when I deleted it, I thereby lost half of the coolant line fitting setup, anyway (not that I wished to keep it, anyway).

FWIW, General Motors' old 350 TPI (L98) motors in the F-Bodies used to have the exact same type of throttle body coolant lines, which were routinely bypassed by just about every F-body owner because of their utter uselessness. The "official" reason (that is, the most widely-accepted version) for their existence was supposedly to help prevent the throttle body from icing up and sticking in cold temps (or so the legend goes); Ford's decision to use a similar design in almost exactly the same years of production was almost surely for the same or similar theoretical purpose (1986-1993 EFI 5.0's, versus the 1985-1992 TPI 305 and 350 ... dunno if later LT1's and '94+ 302's still had it). Given the fact that 4.6's nowadays don't have such EGR coolant accommodations probably has to do with the use of plastic intakes (which don't soak up heat from the motor, much like a stock EFI intake with a phenolic spacer) ... or maybe because they just eventually figured that it was a waste of engineering.

Also ... aren't the Explorer and GT-40 intakes missing these coolant connections?

Darkwriter77 said:

FWIW, General Motors' old 350 TPI (L98) motors in the F-Bodies used to have the exact same type of throttle body coolant lines, which were routinely bypassed by just about every F-body owner because of their utter uselessness. The "official" reason (that is, the most widely-accepted version) for their existence was supposedly to help prevent the throttle body from icing up and sticking in cold temps (or so the legend goes); Ford's decision to use a similar design in almost exactly the same years of production was almost surely for the same or similar theoretical purpose (1986-1993 EFI 5.0's, versus the 1985-1992 TPI 305 and 350 ... dunno if later LT1's and '94+ 302's still had it). Given the fact that 4.6's nowadays don't have such EGR coolant accommodations probably has to do with the use of plastic intakes (which don't soak up heat from the motor, much like a stock EFI intake with a phenolic spacer) ... or maybe because they just eventually figured that it was a waste of engineering.
?

Click to expand...

Does anyone know how the egr gasses are routed on a 4.6? I don't think they come up to the TB do they?


I have never heard of a TB icing over.
In the days of carbs, it was a known problem, but extremely rare.
Most likely, the 'Icing TB' theory is somewhat of a throw back from the 'old timers' trying to relate a carb to a TB.
unfortunately the physics between what happens in a carb is dramatically different from what happens in a TB.


I have found several emissions papers published by SAE, which describe the purpose of the TB coolant lines as having a cooling affect on the egr gasses.
SAE papers are written by professional automotive engineers. Before the papers are published they are reviewed by other automotive engineers for accuracy.
I trust SAE papers completely.



Just my .02 though

jason

In what I have read, I stand-by what I have posted before and agree with Jason. I might have some info saved somewhere.

If de-icing was a concern, a heat riser would be used (exhaust gets hot faster than cold coolant [in circumstances where icing is an issue]).

:OT: Mike, congrats on the mod status (I didn't know that you had taken a break from moderating. You were one when I joined. ). Wait, I know; they made you take time off for the whole Mark VIII fiasco.

Seriously, congrats on that.

Boss 351 said:

my guess is if you want a real cold intake you need to block off the EGR from the lower intake or the heads and then remove the coolant lines...

Click to expand...

Exactly, if you havn't done both, you havn't really done anything in terms of cooling intake manifold temperatures.

Just from reading on this issue over the years.

If the EGR is working,most noobs think that the coolant lines are a source of unnessary heat so they disconnect them.

What they don`t understand is that the hot exhaust gasses being routed through the hidden manifold passages and EGR spacer are a lot hotter than the engine coolant.

The coolant lines are there for a purpose if the EGR is working.
The purpose is to remove excess heat.

Not hard to figure out.

Again, this is one of those things that's entirely theoretical and subjective, until someone can generate some hard numbers or concrete evidence that definitively states one way or the other that one should or should not bypass the coolant lines going to the EGR spacer.

Until then, I think all we're going to hear is a lot of theories, testimonials, and educated guesses. The way I see it, do with it as you will, because I haven't yet heard of anyone who's caused their motor any ill effects by doing or not doing this.

I have an old MM + FF magazine from 1993 here and they mention one potential ill effect from disconnecting the lines.

Quote......
"when this is done,the exhaust gasses are allowed to elevate the intake manifold temperature,causing the engine to ping under heavy load because the air charge temperature is so high".

Ummm ... maybe this has something to do with the high-RPM pinging/smoke issue I just posted 30 seconds ago? (Suddenly, I'm starting to feel really, really dumb...)