Cracked engine manifold - should I be worried?

[eSDee]

I took in my 98 Tacoma for major service, 30K miles the other day. I got a Check Engine light so I was hoping that a my periodic major tune-up would take care of the light. When they inspected the truck they said that I have a cracked manifold, and that it would cost about $550 to replace. I told them to hold off. When I got back in my truck still had the Check Engine light on, but after about 5 minutes driving it went away.

My truck runs decently but I have noticed that I don't have as much power as I once did. It feels like I am running on 3 cylinders instead of 4 (it's not the toughest truck I know this). Could this lack of power be because of my cracked manifold? How big of a job is it to replace it? Should I go to a regular garage rather than Toyota to get it fixed, so that I can save some scratch?

Thanks. I am obviously not much of a mechanic.

*edit* I am probably going to get a new car at the end of the year, and keep my pickup as a backup ride.

[mechmike0034]

The cracked exhaust manifold could indeed be the cause of both your lack of power and your Check Engine light. Your fuel mileage is probably down a little as well.

You don't want to try to replace it yourself if you aren't real handy with dealing with rusted or broken manifold studs. Got | Oxyacetylene Torch?

See Brad at Petersen Automotive (http://ourautoshop.com) in Escondido...

[johnnymk]

Does this cause a faulty signal to the oxygen sensor?

[mechmike0034]

Does this cause a faulty signal to the oxygen sensor?

Yup - each negative exhaust pulse (exhaust actually "flutters", which is a simplified explanation) draws in extra oxygen from the air outside the manifold. This skews the sensor readings.

The engine control computer "knows" what normal oxygen sensor readings should be, plus an OBD-II vehicle actively self-tests emissions-related systems. Errors in these test routines and readings cause the Check Engine light and reduced power.

Note again that this is a VERY simplified, fifty-thousand-foot overview of the process.

Toyota oxygen sensors are discussed at length in this .pdf document... (http://www.autoshop101.com/forms/h37.pdf)

[eSDee]

Thanks Mechmike! I definitely wouldn't be up to doing it myself. But I'll check out your friend if my guy down the street doesn't do it. Should I tell him that mechmike sent me? ;)

[Napoleon54]

wow, 10yo truck only has 30k miles on it?

[DarkFury]

wow, 10yo truck only has 30k miles on it?
For some of us, trucks are the "accessory vehicle" not the daily driver. :D

Although I agree, that's pretty low mileage. :)

[eSDee]

Oops I was unclear. It has been 30k miles since my last big tuneup. I've actually got 130K on it!

[DarkFury]

Heh. :D

Yeah... he's beatin' the dog crap out of it.

My truck is almost 4 years old now (got it in Nov 2003 as an '04 model) and it only has 24,000 miles on it.

[Napoleon54]

Oops I was unclear. It has been 30k miles since my last big tuneup. I've actually got 130K on it!

Ah okay, that makes sense too.

<-- duh! :P

[attgig]

check the rest of the exhaust as well. I had problems with the pipe to the muffler, got that replaced. and then slowly, each piece all the way to the muffler went over the course of 6 months. I wish I just got everything replaced at once.

[eSDee]

check the rest of the exhaust as well. I had problems with the pipe to the muffler, got that replaced. and then slowly, each piece all the way to the muffler went over the course of 6 months. I wish I just got everything replaced at once.

Thanks buddy. I'll have the rest of it checked out as well :thumb:

[mechmike0034]

Should I tell him that mechmike sent me? ;)

Just tell him Mike from Alabama sent you.