Safe to Drive Family XC? Exhaust Manifold Crack

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WillsYoda

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Is it safe for my family to drive in my 98 1mzfe toyota avalon on a cross country trip with a rear exhaust manifold crack? The crack is large enough to where we can smell exhaust in the car IF AND ONLY IF we have the fan on set to "outside air" (the rear exhaust manifold is just below the outside air intake). If we use "recirculating air" with the AC or heat on full blast, even my wife (with a very sensitive sense of smell) cannot smell anything in the car.

I have installed a chemical CO (carbon monoxide) detector (the Pro-Lab CA101 Carbon Monoxide Test Kit) in the car, and it shows nothing when I drive around all day. It is pretty sensitive for detecting CO at low levels.

In about 15 months we will get a perfect car from a family member who lives in the rust-free south, so we do not want to buy another car just yet. The avalon runs great and is comfortable on long road trips. Except for the manifold crack, it is in tip-top shape. I do not want to fix the crack for a number of reasons. The bolts are very rusted (driving in the rustbelt for 19 years), and I'd probably crack a couple in the head for sure. I took it to two mechanics and they said the same: they could fix it for about $1200 if no bolt snapped, but if a bolt snapped then it could get very expensive. It is really tight down there and the head might need removal if it snapped. I just did an Aisin kit for all the seals, belts, and water pump last year. It has 210k miles on it.

We will drive an 8 day road trip with the kids this summer (4 4-hour days each way).

Do you think this is safe with the exhaust manifold leak? Right now the kids have been limited to being in the car about 15 minutes max with this leak. I'm wondering if it is a good idea to spend so much time in the car, even though there is no smell and the CO chemical detector (which is supposed to be far more sensitive than an electronic in-home CO detector) does not detect anything.
 
Originally Posted By: Kool1
How about JB weld on the crack to temporarily stop the noise and prevent exhaust gas from leaking?


+1. If youve git a plan for replacement, why not try to band aid?
 
Originally Posted By: Kool1
How about JB weld on the crack to temporarily stop the noise and prevent exhaust gas from leaking?


I thought of that but I'm told it cannot be done. The crack is invisible from the outside. I think the crack is under something, or maybe it is just the seal. I've taken it to two mechanics who can hear the leak with a stethoscope and think it is a crack, but they cannot see it (except for the exhaust that visibly leaks from around the manifold).

But no one has seen the crack and no one knows where it is. I kept asking where it is and both mechnics said "we can't know where it is."
 
Originally Posted By: rooflessVW
Junkyard manifold and a weekend of swearing.

Fix the car.


If I lived in NC it would be easy, since they do not salt to roads like crazy for 6 months a year. But this car has been bathed in salt water for 6 months a year for 19 years. The bolts are so rusted they would snap in the head. I have a friend who has done this dozens of times in the saltbelt, and he says that 9 times out of 10 a bolt snaps into the head.
 
My exhaust manifold bolts are rustier than this guy's with his F150... https://www.f150forum.com/f6/really-rusted-header-bolts-should-i-even-go-any-further-219488/

The F150 guy snapped all but one bolt after soaking in PB blaster and liquid wrench for a week. Lucky for him there is room in an F150 to drill it out. There is absolutely no room in the 1mzfe rear exhaust manifold. The head would need to be pulled.

Basically, my friend and two mechanics are convinced that the only way to do the job is to pull the head, which is too costly to bother.
 
You are correct to be concerned. My suggestion: Don't mess with CO. Fix it ($$$), borrow a car for this trip, or rent a car.
When you get rid of the car in 15 months, be sure to disclose the issue for safety's sake.
This is an unfortunate situation - I hope a mechanic on this site can offer a lower-cost solution for you.
I doubt the car is worth the $1200 cost of repair.
 
Originally Posted By: SWS
You are correct to be concerned. My suggestion: Don't mess with CO. Fix it ($$$), borrow a car for this trip, or rent a car.
When you get rid of the car in 15 months, be sure to disclose the issue for safety's sake.
This is an unfortunate situation - I hope a mechanic on this site can offer a lower-cost solution for you.
I doubt the car is worth the $1200 cost of repair.


It would be about $900 to rent a car from the trip (which will be about a month, aside from the driving days). I don't think we can borrow a car from anyone. I think one way or the other this will cost us $1000 bucks or more.

We will definitely disclose the problem to any buyers.
 
I now remember why it is IMPOSSIBLE for me to patch the exhaust manifold on a 1mzfe. Not only is it crazy tight, but the cast iron manifold is tightly wrapped like a glove by a stainless steel sheath. It is impossible to pull off that sheath and see where the crack is.

So it is not possible to patch it. A mechanic explained this to me, but I did not remember exactly why until I took another look today. This is true for all 1mzfe manifolds. So patching is not an option. Replacing the manifold most likely requires removing the rear head, according to 3 mechanics I trust. That is thousands of dollars, far more than the car is worth.

So it looks like there are no good options here. Either I live with the leak or junk an otherwise great car. I don't mind the leak if I drive the car alone, but I am concerned for my kids, especially on long trips.

It is really too bad, since in 15 months we can get a great car from a family member.
 
Hack apart the heat shield, putty the exhaust, then patch the heat shield back together with hose clamps or similar macgyvering.
 
Originally Posted By: eljefino
Hack apart the heat shield, putty the exhaust, then patch the heat shield back together with hose clamps or similar macgyvering.


I'd need to remove the manifold to do that. At that point I'd just need to replace it with a junk yard piece.
 
Sell it as is, someone will buy it. Maybe find a deal where someone wants to dump a lease and has 15 months on it.

I had a manifold crack & leak on 94 Camry. It was better when engine was hot and things expanded. Never bothered me and sold it like that at a little over 200k miles. I could never smell it.
 
Originally Posted By: Donald
Sell it as is, someone will buy it. Maybe find a deal where someone wants to dump a lease and has 15 months on it.

I had a manifold crack & leak on 94 Camry. It was better when engine was hot and things expanded. Never bothered me and sold it like that at a little over 200k miles. I could never smell it.


It does get better when the engine is hot. It seems to seal itself a bit on longer trips.
 
Find the leak first. It could just be a blown gasket from the manifold to the pipe or a hole in the pipe.

Mechanics see some problem behind the engine on an old side-mounted Camry V6 and just want to be rid of you. They know they'd want to charge more than the car is worth to mess with it.
 
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