This post will contain spelling and grammar errors that I may or may not edit once this job is done. But for now I'm on day two (13 hours yesterday and 14 today) of a project that's been sitting in boxes in my garage for a year.
I purchased Doug Thorley long tube headers for the 03-04' gx470 with no secondary air pump tubes. I bought a Hewitt Tech SAIP module to bypass the pump and opted to remove all the associated plumbing. (More on that to follow).
I got URD mid pipes to match to my headers and a Gibson catback exhaust to finish it. My goal was for a nice V8 growl without being too loud and no drone (Time will tell).
Header removal was atrocious. I've done Jeep headers, BMW M3 headers, Audi S4 headers so this job is not foreign to me. Lexus just seemed to put every suspension component and wire loom in the way of all the header bolts. I followed the instructions and started on the passenger side. It was a nice warm up for how s***ty the driver side was going to be. Passenger side came out in about 3 hours. Driver side took about 7 hours. I had 3 nuts strip on the driver side and of 7 of the 8 manifold studs backed out.
A thin wall long neck spiral extractor for the stripped nuts off after lifting the engine gave a straight line to the bolt. Fan shoud will contact the fan and one will break so don't try to hoist the engine more that 2" without removing the fan or shroud.
I replaced the studs that backed out with M10x1.25 studs of the same length and opted for JIS stainess notched flange nuts. I'll do a dab of red loctite on the bolts as blue with burn off with the manifold heat.
Problem I discovered once the headers were ready to reinstall is the 05-09 with the exhaust tubes actually have ports in the cylinder heads, not ported from the headers. This means I'll have open ports, which is a no-go. I send the headers I got a year ago back, which is a no-go. Or, I template the gasket, cut steel blockers and weld them to the header. I opted for "C".
I used the gasket as a template (rough face towards the header). (Made that mistake once!). Once I had my piece cut, I clamped the header to my table, aligned the blockers, clamped those (to prevent warping) then tacked them down.
Once cooled, I pulled them, test fit to ensure the ports were covered, then clamped everything back up and ran beads. I'm using flux as I'm out of gas and some research said it's better on stainless, but who knows, and it's all I had. Penetration looks good and the welds look solid. I'll finish header #2 tomorrow then start reassembling.
I have a 250 amp alternator getting delivered tomorrow that will go in while there's access also. Then I'll install the air pump module and start her up. Fingers crossed.
Additional notes:
When doing this job, make sure you have a healthy selection of extensions and swivel adapters. For me the most common used was 1/2 inch. I have an impact rated 14mm tapered socket that I ground the face down on (removed the bevel from the socket to give better purchase on the nut). This is a must. I stripped 3 nuts before doing this. Also, definitely do not use 12-point sockets on the exhaust nuts, they will strip.
Removing the motor mount bolts was necessary, but I found I did not have to remove the motor mount brackets from the motor side.
I'll add more if I come across more useful tips.
I purchased Doug Thorley long tube headers for the 03-04' gx470 with no secondary air pump tubes. I bought a Hewitt Tech SAIP module to bypass the pump and opted to remove all the associated plumbing. (More on that to follow).
I got URD mid pipes to match to my headers and a Gibson catback exhaust to finish it. My goal was for a nice V8 growl without being too loud and no drone (Time will tell).
Header removal was atrocious. I've done Jeep headers, BMW M3 headers, Audi S4 headers so this job is not foreign to me. Lexus just seemed to put every suspension component and wire loom in the way of all the header bolts. I followed the instructions and started on the passenger side. It was a nice warm up for how s***ty the driver side was going to be. Passenger side came out in about 3 hours. Driver side took about 7 hours. I had 3 nuts strip on the driver side and of 7 of the 8 manifold studs backed out.
A thin wall long neck spiral extractor for the stripped nuts off after lifting the engine gave a straight line to the bolt. Fan shoud will contact the fan and one will break so don't try to hoist the engine more that 2" without removing the fan or shroud.
I replaced the studs that backed out with M10x1.25 studs of the same length and opted for JIS stainess notched flange nuts. I'll do a dab of red loctite on the bolts as blue with burn off with the manifold heat.
Problem I discovered once the headers were ready to reinstall is the 05-09 with the exhaust tubes actually have ports in the cylinder heads, not ported from the headers. This means I'll have open ports, which is a no-go. I send the headers I got a year ago back, which is a no-go. Or, I template the gasket, cut steel blockers and weld them to the header. I opted for "C".
I used the gasket as a template (rough face towards the header). (Made that mistake once!). Once I had my piece cut, I clamped the header to my table, aligned the blockers, clamped those (to prevent warping) then tacked them down.
Once cooled, I pulled them, test fit to ensure the ports were covered, then clamped everything back up and ran beads. I'm using flux as I'm out of gas and some research said it's better on stainless, but who knows, and it's all I had. Penetration looks good and the welds look solid. I'll finish header #2 tomorrow then start reassembling.
I have a 250 amp alternator getting delivered tomorrow that will go in while there's access also. Then I'll install the air pump module and start her up. Fingers crossed.
Additional notes:
When doing this job, make sure you have a healthy selection of extensions and swivel adapters. For me the most common used was 1/2 inch. I have an impact rated 14mm tapered socket that I ground the face down on (removed the bevel from the socket to give better purchase on the nut). This is a must. I stripped 3 nuts before doing this. Also, definitely do not use 12-point sockets on the exhaust nuts, they will strip.
Removing the motor mount bolts was necessary, but I found I did not have to remove the motor mount brackets from the motor side.
I'll add more if I come across more useful tips.
Last edited: