Doug Thorley Shortie Headers 4.7L V8 - My Experience w/ Install & CA Smog

[cyclingtrav]

What's up y'all. Just wanted to share my experience with installing my Doug Thorley Short Tube "Shortie" headers and dealing with SMOG inspection in California.

TL;DR- These headers are CA-legal per CARB Executive Order D-5470-7. When the smog tech asks for a "sticker", tell them to put the vehicle in a lift and see the EO number on the oval tag that's stamped on the header tube. My smog tech was giving me grief and demanded a sticker in order to pass it. The badge/stamp is visible in the first photo below.

I'll include part numbers below for all OEM parts ordered/replaced with this job.

I bought my '08 V8 in December '23 knowing that it had an incessant ticking noise from the headers being "bad", but I didn't know it would prevent me from passing CA smog. It wasn't clear what specifically was causing the issue- if the headers themselves had cracked, if the gasket had failed- but I knew they needed replacing. Emissions testing all passed, but the smog tech failed me under "Other Emission Related Components/Systems" based on "Upstream exhaust leak, before catalytic converters."

I ordered the headers. DT accidentally sent the wrong gasket set with them, but they were proactive in sending the correct gaskets with express shipping. Much appreciated!

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My mechanic buddy was a little concerned about the QC of the headers. He said the machining on the face of the flange wasn't clean, and that the gasket quality was questionable (it actually broke in half when he dropped it into the header shipping box with packing cushion). He ended up using a small amount of high-temp gasket maker between the header flange and OEM gasket before installing.

He also mentioned that there were globs of ceramic coating or some compound on the threads for the bolts that secures the SAIS air tubes. Be sure to chase these before installing the headers as they're pretty difficult to get to.

<a href="https://ibb.co/TmYZd5s"><img src="https://i.ibb.co/qk7zVwv/Resized-Resized-20240203-131218-1706994743615-1706994744916.jpg" alt="Resized-Resized-20240203-131218-1706994743615-1706994744916" border="0"></a>

<a href="https://ibb.co/JpMqWRw"><img src="https://i.ibb.co/PWfMsZv/Resized-Resized-20240203-132852-1706995737920-1706995738937.jpg" alt="Resized-Resized-20240203-132852-1706995737920-1706995738937" border="0"></a>

Per DT's recommendation, I ordered replacement engine mounts since the install requires lifting the engine in order to remove/replace the headers. The old ones weren't in bad shape, but it's a good time to do it while the engine is out of position. We replaced the two air tube gaskets for the SAIS connection to the tube on top of the header assembly.

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My 4R was originally imported to Canada by the first owner, who then imported it to the states in Washington. It definitely survived a fair amount of cold weather abuse as evident by the installed block heater and seized manifold nuts to studs. All the studs came out whole, but not one of the nuts broke loose from their stud on either side. Fortunately, I ordered a complete set of nuts and studs as a precaution.

<a href="https://imgbb.com/"><img src="https://i.ibb.co/HHGvP5q/Resized-Resized-20240203-155436-1707004482790-1707004484073.jpg" alt="Resized-Resized-20240203-155436-1707004482790-1707004484073" border="0"></a>

When my mech got the original manifolds off, he determined that it was the frontmost passenger side manifold tube that had completely rusted out and the insert inside the tube had fallen out. The driver's side gasket had also failed. Important note: he said he wasn't able to remove the driver side without pulling the driveshaft.

<a href="https://ibb.co/Fn35L3T"><img src="https://i.ibb.co/zNxXTxv/Resized-Resized-20240203-183024-1707013832012-1707013833206.jpg" alt="Resized-Resized-20240203-183024-1707013832012-1707013833206" border="0"></a>

<a href="https://ibb.co/56yJx0G"><img src="https://i.ibb.co/DtyjgJz/Resized-Resized-20240203-161526-1707005733557-1707005735001.jpg" alt="Resized-Resized-20240203-161526-1707005733557-1707005735001" border="0"></a>

He test fitted everything and spot welded for the cat placement on the collection tubes, removed it all and fully welded the cats to the collection tubes.

<a href="https://ibb.co/hD0sQQQ"><img src="https://i.ibb.co/V26Vnnn/Resized-Resized-20240203-223208-1707028338716-1707028339816.jpg" alt="Resized-Resized-20240203-223208-1707028338716-1707028339816" border="0"></a>

Here they are installed:

<a href="https://ibb.co/0sRyyzG"><img src="https://i.ibb.co/Y0FBBVL/Resized-Resized-20240204-004535-1707036367079-1707036368037.jpg" alt="Resized-Resized-20240204-004535-1707036367079-1707036368037" border="0"></a>

<a href="https://ibb.co/VBNtHcR"><img src="https://i.ibb.co/SvxPQ4b/Resized-Resized-20240203-222221-1707027750879-1707027752158.jpg" alt="Resized-Resized-20240203-222221-1707027750879-1707027752158" border="0"></a>

My mechanic said this was one of the top three worst jobs he's done, just a huge pain in the ass. At first, he said book quoted 14hrs. Then, based on the instructions from DT, he'd probably be able to do it 7-8. Add in the seized manifold bolts and welded exhaust (previous owner had all the bolts on the exhaust connections welded on??) it ended up taking him the full 14 hrs or so. He also said he wouldn't do this job again for the amount he quoted me knowing now what all it entails.

He confirmed there were no leaks after the install was complete. The day after I picked it up, I went to the smog station and successfully got my smog certificate (see earlier note on how to explain to smog tech exemption for these aftermarket headers) and went straight to AAA to take care of the title transfer and registration renewal. It's driving well, maybe slightly more power and more consistent power through the rpms.

I hope this helps anyone with a V8 in California trying to decide what route to go when repairing cracked headers. The only thing I'd have done differently would have been to also replace the upstream O2 sensors, but given they're pretty easily accessible from the wheel wells I'll take care of those soon.

Here are the oem part numbers for everything else needed for the install:

90080-12008 Exhaust Manifold Stud (x16)
90080-17187 Locking Nut (x16)
17198-50010 Exhaust Manifold Gasket (passenger side)
17173-50030 Exhaust Manifold Gasket (driver side)
17376-50010 SAIS Air Tube Gasket (x2)
12361-50190 Motor Mounts (x2)
89465-35690 Upstream O2 Sensors (x2)​

 

[imwatchinusleep]

They look real nice, except for the manifold face - I would agree with your mechanic on that.

Would be interested to see how soon before they start to rust. I need to do my passenger side on the 05 V6 since its cracked, not looking forward to it.

 

[cyclingtrav]

I'm in a pretty temperate climate and will be using my 4R to get up to and back from Lake Tahoe for ski/snowboard season mostly. I don't suspect rust will be any sort of issue for me with the ceramic coating.

 

[vonRunner]

Great write up and information! I've been wanting to put shorties on mine (I'm also in CA), but I only ever see info on long tubes. Thanks for taking the time to document/share this :cheers:

 

[mrmclovinjr420@gma]

Hi Great post, i just purchase my 08 v8 240k 4RUNNER and i do hear ticking sound when i start it for the first 1min, luckily i passed smog but sooner or later i will need to change the header, do you mind sharing the cost and also where you get the work done since your tech have EXP with this is a good start point for me thank you so much for posting this http://www.mysmiley.net/imgs/smile/party/party0021.gif

 

[cyclingtrav]

do you mind sharing the cost and also where you get the work done since your tech have EXP with this is a good start point for me http://www.mysmiley.net/imgs/smile/party/party0021.gif

Congrats on your new 4R! My guy said he wouldnÂ’t do this job again because of how many things can go sideways, so I canÂ’t share where I had it done. He charged me $1,400 labor.

YouÂ’ll have better luck at smaller shops that can weld or exhaust-specially shops.

 

[rdruss]

Congrats on your new 4R! My guy said he wouldnÂ’t do this job again because of how many things can go sideways, so I canÂ’t share where I had it done. He charged me $1,400 labor.

YouÂ’ll have better luck at smaller shops that can weld or exhaust-specially shops.

So, did you reuse your original cats and have them re-welded to the headers?

 

[cyclingtrav]

So, did you reuse your original cats and have them re-welded to the headers?

Yeah I reused my original cats. The DT instructions tell you to cut them far enough up the tapered portion to have space to insert the collector tube.

My mechanic said visually they looked to be in good shape… but about 6 months later, I got a p0420 code. Its intermittent though, and Ive had good luck with doing the battery-unplug-replug trick to reset fuel mgmt baselines and driving around long enough to get a full cycle to pass smog. I replaced all my AFR/O2 sensors and am now trying a couple rounds of Cataclean to find out for myself if its snake oil or not- so far it hasnt come back *fingers crossed*.

Quick note: if you plan on doing the header replacement, replace your upstream AFR sensors while theyre in there. Once the headers are in, its very difficult to get to the sensors without a shop lift.

 

[Runnin on E]

Yeah I reused my original cats. The DT instructions tell you to cut them far enough up the tapered portion to have space to insert the collector tube.

My mechanic said visually they looked to be in good shape… but about 6 months later, I got a p0420 code. Its intermittent though, and Ive had good luck with doing the battery-unplug-replug trick to reset fuel mgmt baselines and driving around long enough to get a full cycle to pass smog. I replaced all my AFR/O2 sensors and am now trying a couple rounds of Cataclean to find out for myself if its snake oil or not- so far it hasnt come back *fingers crossed*.

Quick note: if you plan on doing the header replacement, replace your upstream AFR sensors while theyre in there. Once the headers are in, its very difficult to get to the sensors without a shop lift.

You might want to check the torque of hardware for the headers and flanges. The first trouble shooting suggestion in the FSM for a P0420 is "gas leakage from exhaust system" Since you have anew install it might just be loose from heat cycles.

 

[yourfriendcasey]

I was doing my valve covers last night and accidentally punctured my exhaust manifold when drilling/tapping out one of the valve cover bolts that snapped off..

Been a rough couple of days with all the valve cover issues and crazy exhaust leak being revealed when I thought I was finally done was a huge kick in the nuts.

But I think I'm using this opportunity to just say fuggit and get the DT shorties installed.. Im in CA too so sounds like the shorties are the only option for smog.

What is the performance improvement like on the shorties vs the long tubes from your experience? Do you get any more HP/ Torque/ MPG boosts like you do with the long tubes? or is it pretty negligable?

 

[t-rex grrr 2]

thanks for the write-up!

What are you impressions with the new headers?

 

[elshep]

Great write up, Thanks for sharing. After the dreaded ticking and then installing DT shorties, Icant believe I waited so long, no looking back now. Enjoy the Shorties!

 

[cyclingtrav]

thanks for the write-up!

What are you impressions with the new headers?

Dealing with smog (California) was a little bit of a headache because the tech didnt believe that they were CARB complaint. Besides that, maybe a slight improvement in torque? No noticeable difference in sound.