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I have read time and time again about MAC headers causing someone's engine to be destroyed. Theorys are the headers coating is comming off or the welding slag is being sucked up by the EGR. I am by far a modular expert , just a site owner, but I do not recall any of the exhuast gases recirculating through the cylinders. I recall on my 95 GT that the EGR valve opened into a port that ran in the center of the intake, none of the exhuast gases was sucked back into the intake port on the heads. Also if exhuast gas was plumbed back into the intake, wouldn't the intake be smut black inside the runners? I may be wrong but I thought that is how the EGR system ran, and it may well be altogether different on a modular, but I know the modular intakes aren't smut black on the inside either. If that is the case, then how can slag/header coating be sucked back into the cylinders causing engine damage? :confused: :confused: :confused:
 

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here is my experience, put mac long tubes on, as they arrived. normal healthy engine no oil usage. completed the install on a friday, by sunday less than 100 miles, oil usage was 1 quart every 100 miles. if i was lucky.

engine rebuilt under warranty. visible scoring of all cylinder walls and piston. not beleiving that a header can cause this on design alone. i cleaned the primaries out, left the egr connection unplugged for initial start up. i have never had a problem since with these headers. i do use 1 quart every 300 miles if i am on the interstate but this is valve seals. what ever the macs did was not valve seals, i looked like a mosquito truck going down the road. oil accumulated on the rear of the car, plugs fouled.

way back before the corral crashed i was the first to report this and people said i was crazy. i didnt beleive it myself but when lots of other's started reporting the same thing it became more credable.

i have them on the car now, when these rust out, which they will do, i will replace them with something better.
 

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it would be nice to know, i quit trying to figure it out. i just accept it as fact. its someting that only the macs do, bbk users have reported some increase in usage but not to the extent of 1qt per 100 miles. i knew somebody else that put them on same thing that happened to me except his cylinders were not as scored. it almost looked like the rings lost their seat. its a mystery that i just accept as fact. :D
 

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forgot to add, i went back to the stock exhaust before the 1st rebuild and the problem persisted. so whatever damage was done was permanent.
 

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After hearing this over and over, I am believe now that my old 93 Cobra with a 5.0l had the same problem. The engine was very healthy, shortly after installing MAC Longtubes, had serious blowby and needed a short block. I realize it was not a 4.6l, but it sure was strange that I got the concern after installing the longtubes.
 

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first of all...do NOT mention the corral here. That place is for idiots who list "tint" in their mile-long sigs as a performance mod. Secondly, as most people are, I am skeptical.....not that I dont believe you but how could scavageing exhaust gases ruin a motor? This is a weird one..I would love to see how it could happen
 

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The only way I could see the headers causing a oil consumption problem would be from the welding slag being left in the headers. It is then possible for it to be sucked up the EGR tubes and into the engine, I guess. FWIW I have Mac headers now and I had them on my old 302 with no problems whatsover. Then again, I had no EGR either :cool:

I highly doubt it is from scavenging, some of the guys that had the problem observed cylinder wall scoring and that could not be cause by "over" scavenging.
 

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I am not referring that the scavageing of exhaust gases caused my concern. There are many other longtubes out there that have way better scavageing than Mac's, without issues. With the 302 motor I was still using the egr, and I believe that it could have been from possible weld slag or debris. Who really knows, it could have been anything. Just odd coincidence.
 

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MAC HEADERS

I BOUGHT A 99 COBRA WITH 19,000 MILES, PUT ON MAC FULL LENGTH HEADERS AND MATCHING H-PIPE. BEFORE 20,000 MILES MY CAR WAS SMOKING LIKE CRAZING. I THOUGHT I CRACKED A RING OR SOMETHING SO I SENT IT TO SHOP. UPON TEAR DOWN IT LOOKED LIKE MY RINGS WAS WASHED OUT AND NOT SEALING. I COULD NOT FIGURE IT OUT BUT MAYBE IT WAS THE HEADERS AND H-PIPE.
 

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Just for the record, I have a blown 96cobra, 68k on it now, at 60k I bought and installed mac long tube's,mac cats and pro dumps. I was using about 1qt every 1000 or so miles. I'm still using about the same amount. Maybe i'm a lucky one?
 

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well...

...Ive got Mac L/T's on my 2V (sorry, I know this is a 4V page, but it was slow on the sohc side) and other than ther coating suxx's(rusted @ 1 month). I have 0 problems... I too dont understand how the install of L/T's would cause engine problems, if welding "slagg" did get through they would have to be damn small particles and I think they, if any would go right back out the exhaust...maybe wth the improved scavenging on the exhaust it could be pulling oil past the exhaust valve guides & seals?
the only reason I bought them there were cheap($$$) and easly gotten, won't make that mistake again:D

Randy Stinchcomb

p.s. get use to me:eek:

p.s.s. I also have great prices on Ford parts !!
(is this allowed?:) )
 

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p.s.s. I also have great prices on Ford parts !!
Randy, welcome aboard man!!! We have no problem with vendors being on our board and welcome it. We have a forum specifically for posting specials you are running or just general advertisment.

Chad
 

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I think Randy is on the right track here...If the MAC headers are sooo efficient, in the scavaging effect, they are in effect, pulling oil past the valve seals and guides...The junky stock iron valve guides that Ford uses, don't hold up too well...The headers, could be pulling too much oil past the guides, causing them to deteriate to point of allowing excess oil in the combustion chamber, causing the rings to not seat and other possible problems..ONce the excess oil is in the combustion chambers and in the cylc walls, without a vaccuum pump, the damage is going to be bad..This is just a theory, and I find it hard to believe that a mundane set of headers would do this... IMHO..


Jeff
 

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ModMan said:
first of all...do NOT mention the corral here. That place is for idiots who list "tint" in their mile-long sigs as a performance mod. Secondly, as most people are, I am skeptical.....not that I dont believe you but how could scavageing exhaust gases ruin a motor? This is a weird one..I would love to see how it could happen
Try doing at search at the Corral. :turd
 

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It is NOT from bad seals. Mac's QC sucks, and the engine failures are coming from slag and God knows what, that they've left inside those tubes. I ground the weld beads down, as well as all the slag, and flushed them out liberally before installing them. I've had no problems with oil consumption. I actually use less oil now than before.
I don't believe the crap is getting sucked through the EGR, and if it did, all the oil in the lower plenum would catch most of it before it got sucked in the runners. I believe it's getting sucked in, or I should say, thrown in, by the resonant waves in the primaries.
 

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MAC Headers

I know this is about 4v's, but my 97 GT had no problems like the ones listed in this thread and I have MAC long tube headers with 3" collectors, 3" Pro Chamber off road for long tubes, and 3" MAC flowpath catback. I guess this only happens to Cobra 4v's with MAC's. I just don't understand it myself, but if all these cars were a'ok before the MAC install and after used oil, then It must have been part of the problem.

A guy on the corral (Boss 330) said he found it to be the valve guides or seals (I don't recall which) when he had a problem like this (if I'm correct so don't quote me). Just my 2 cents - John
 

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32VHEMIJR said:
It is NOT from bad seals. Mac's QC sucks, and the engine failures are coming from slag and God knows what, that they've left inside those tubes. I ground the weld beads down, as well as all the slag, and flushed them out liberally before installing them. I've had no problems with oil consumption. I actually use less oil now than before.
I don't believe the crap is getting sucked through the EGR, and if it did, all the oil in the lower plenum would catch most of it before it got sucked in the runners. I believe it's getting sucked in, or I should say, thrown in, by the resonant waves in the primaries.
This is what I have thought from the beginning.

There is some kind of debris (slag or such) in the headers that is getting sucked into the chamber, or tossed in, however you want to look it at. I actually had the same issue on a 302 car with MAC shorty headers.
 

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I had Mac long tubes put on my 96 cobra 6 years ago. i had no problem with them....just had my motor rebuild a few month ago and the Mac's started leaking a bit, so i junked them and got some Cooks...maybe i just got lucky
 
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