Nissan Frontier Forum banner

Exhaust Manifold Cracked Again!!!

10K views 30 replies 12 participants last post by  Steveie 
#1 ·
Yes, it's another post about exhaust manifolds. I did a search looking to see in anyone else encountered this issue and I didn't find anything. All posts I saw about exhaust manifolds were asking how much labor, cost, best parts, etc.

I've replaced both exhaust manifold and they are already cracked in basically the same spot as the old ones. Lucky I never threw them out and was able to compare. The Passengers Side I installed in May and the Drivers Side in July. What would cause this to happen? One thought I has was that the flow out of the catalytic converter is limited causing it to heat up. It always seems to be too hot under the hood. Another thought was that maybe gas is not infighting in the chamber and then igniting out the exhaust. It has a random rough idle that I've been chasing or years to officially fix.

I'm open to all ideas.

Thanks in advance.
 
#4 ·
so the 1rst gen Frontiers are well known to have cracked headers. they were even replacing them under warranty. my old 1rst gen both header cracked by 40,000 miles, with much bitching the dealer replace both on their cost.. then at 52,000 miles they both were cracked again, i am not talking one crack.. the left side literally fell into about 7 different pieces when i finally unbolted it all. of course the dealer would not do it again so i went for a aftermarket set of long tube headers that eliminated the first set of cats. I did have to buy the extended bung for the O2 sensors. truck ran amazing with them. and i owned the truck until 230,000 miles and both headers were in perfect shape still. the casting on the stock headers is garbage and extremely thin in certain spots.. like 1/16th" If i were you i would look into a set of aftermarket headers if you plan on keeping the truck for a while. and they are WAY cheaper than stock
 
  • Like
Reactions: butterman2473
#6 ·
I was thinking about Headers. I finally found the receipt and O'Reillys has new Dorman cast iron ones coming tomorrow. I'm back and forth on keeping the truck. I feel like I'm always fixing it. I have approximately 198k on the truck.

If I do Headers do I need to wrap the pipes to cut down on heat in the engine bay?
 
#11 ·
I'm probably going get the Black Hours Racing Header listed in my last post. The other webpage I noticed that they are out of stock. What ever one I get from I'll see what they recommend with wrapping. Dough Thorley's are just out of my price range right now.
 
#12 ·
Steel headers can be wrapped, but I don't believe wrapping is recommended nor required on ceramic coated headers.
 
#13 ·
I've never had it happened to me personally, but I've been on enough car forums to see that wrapping your exhaust manifold/headers can make them crack due to the wrap holding onto moisture over time.
 
  • Like
Reactions: Fredx
#15 ·
I cracked one due to some deep cold water and a fast entry on a back road one rainy cold night (whoops). I seem to recall it cost about 1300 bucks to repair. At the time I had a basic tool kit (one of those craftsman 130 piece things) and lived in an apartment. Also compounding the issue is it was the official winter time in North Texas, so it was rainy and cold as well. Looking back, if it happened today, I would take it off and tig it back up, and then if it broke again I would probably already have a set of headers on the way, lol.
 
#19 ·
I decided not to go with the cheap headers. ProTuningLab is out of stock and not sure when their supplier will send them more inventory. I found BlackHorse-Racing also on ebay and they had terrible reviews. Poor quality parts. My guess is a China company.

I put the warranty exhaust manifolds on today. It went much smoother this time. No suck or broken hardware.

If you're every putting on both exhaust manifolds it easier to unhook the exhaust after the Y. Then you can shift the exhaust back to gain access to the bolts attaching the manifold to the block. There is a bracket right near where 2 exhaust pipes connect together. Once disconnected the exhaust from the muffler back can be shifted towards the drive shaft and out of your way. I used a fully extended jack stand to support it. Just hangin kept getting in my way.

Could worn or old engine mounts be what caused the exhaust manifolds to crack that quickly? My truck has close to 200k miles and the mounts are original.
 
#20 ·
Both Exhaust Manifolds cracked in basically the same place. Top Manifold is the original one. Bottom is the one I replaces a few months ago.


1st picture is the Drivers Side

2nd picture is the Passengers Side

324960

324962
 
#21 ·
While you're at it, make sure your motor, transmission, and exhaust mounts/bushings are all in good condition. Avoid any aftermarket parts that aren't custom made here in the USA. Anything generic listed on Ebay or similar sites are all "rebranded" Chinese parts. As with all products, you'll have some that may last, but you're more than likely to have fitment issues or quality issues down the line compared to something of much higher caliber and cost.
 
#23 ·
I’ll keep that in mind. Usually I can tell if it’s a company selling poor quality parts. I’m all about getting a good deal. But not when it’s junk.
While you're at it, make sure your motor, transmission, and exhaust mounts/bushings are all in good condition. Avoid any aftermarket parts that aren't custom made here in the USA. Anything generic listed on Ebay or similar sites are all "rebranded" Chinese parts. As with all products, you'll have some that may last, but you're more than likely to have fitment issues or quality issues down the line compared to something of much
 
#22 ·
een there, done that. Still have 1 cracked one sitting on the floor in the garage.

I did a full custom exhaust this summer (headers, cats, muffler, etc) - although it's a bit patchy (I used a combination of weld-in parts and factory pipes I had left), I like it so far, but time will tell if the headers hold up (I got the cheap ones...)

Have you tried welding the cracks? Find a fab shop and get someone who knows about metals to weld the cracks? I've heard of that working on the V8 4Runner headers - they develop a small crack as well. I'll probably try that on my 4Runner since it's starting to have an exhaust "tick" too...
 
#24 ·
een there, done that. Still have 1 cracked one sitting on the floor in the garage.

I did a full custom exhaust this summer (headers, cats, muffler, etc) - although it's a bit patchy (I used a combination of weld-in parts and factory pipes I had left), I like it so far, but time will tell if the headers hold up (I got the cheap ones...)

Have you tried welding the cracks? Find a fab shop and get someone who knows about metals to weld the cracks? I've heard of that working on the V8 4Runner headers - they develop a small crack as well. I'll probably try that on my 4Runner since it's starting to have an exhaust "tick" too...
I purchased the exhaust manifolds from O'Reilly's. They were still under warranty. No reason to take them to get welded. I put the new ones on a few days ago. However I think the drivers side may have cracked again. When I put my hand on the hood you can feel a difference of temperature between the passengers and drivers side. Another sign is when it feels like I'm literally cooking in the drivers seat on longer drives (Balls Soup).

I'm really leaning to motor mounts are the culprit. I will pull the heat shields when I have a chance next weekend and see if it's cracked again. I'll also inspect Motor and Transmission mounts.
 
#25 ·
UPDATE

The exhaust manifolds I put on 5ish months ago are cracked again. Every month it get louder. My guess is cracked in the exact same spot as the last 2 I've removed. I'll take pictures once I remove the heat shields to inspect them.

I've decided to bite the bullet and get Doug Thorley headers. I see that they offer Long or Short headers. What is the difference between the 2? Also, should I stick with stock exhaust or get it all re-done?
 
#26 · (Edited)
It's looking like Short Headers will bolt right up. If I get the Long Headers I will have to eliminate the first set of CAT's and add check engine light eliminators on each side.

I was hoping to add Short headers but it seems like everyone is out and is only listing Long headers. Does anyone know where I can find Shorty's? I'm trying to do the work myself and not have to go to an exhaust shop. I know how to put them on. I've put on exhaust manifolds twice already this year.
 
#27 · (Edited)
I called AC (4x4parts) and they said that Long headers will bolt directly on. It takes the place of the exhaust manifold and the first set of CAT's. The only other thing I need to order is the Check Engine Light Eliminator to cancel out the codes that will pop up. They have the best price compared to all the other sites also. Works for me!!!

I'll take some pictures when I install the new headers.
 
#28 ·
Doug Thorley Headers have been installed!!!!!

It took me forever (14 hours). I kept running in to minor issues.

Some things to be aware of when installing.

Use all new studs and nuts. I reused a few stock ones and had no way to get a ratchet in. Also I couldn't get a torque wrench in to tighten the nuts to factory spec. I followed the tightening sequence and went off feel hoping I got everything tight enough. Some spots I had to use an open end wrench to slowly crank down the nut. Specifically the upper nut closest to the firewall drivers side. I will check the nuts in a week to see if any are loose. I have a noise right now that I think may be an exhaust tick. It goes away when I increase the RMS a bit making me think it's not lifters.

Passengers side primary O2 sensor is short. Bung hole is farther away from the harness. I was able to unhook the harness and stretch it just enough to get connected. I will fix that soon. Will splicing and extending the wires effect the signal? Another option is I think I can just get another drivers side primary O2 sensor. That side has longer wiring. Will that work?

Attaching the the bolts provided in the kit to the remaining exhaust can be a little challenging to tighten up.

Heat Shield on passenger side protecting the tubing may rub on headers. Solution bend the metal out of the way.

O2 sensors have an adaptor to fit the stock bung holes. It took me a bit to figure out that I can take them off.

I forgot to put one the Check Engine Light Eliminator at the secondary O2 bung hole. I had already bolted everything back up. So far I have no Check Engine Light/Codes. My truck had 4 Catalytic Converters for a 3.3V6. Does everyone else have the same thing? Is the Check Engine Light Eliminators needed when I leave the 2nd set of Catalytic converter? Or is is for when you only remove all Catalytic Converters.


Over all I'm happy with the Headers(y)(y). Sounds good and no more heat transferring to my floorpan then moving to my seat. Long trips I'd be cooking. NUTS SOUP!!! Chaffed really bad when the drive was over 🤣
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top