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eric
eric, Automotive Repair Shop Manager
Category: Nissan
Satisfied Customers: 24450
Experience:  Automotive Repair Shop Manager, Technician/JA Mentor
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Can catalytic converters on a Nissan Altima 2002 2.5 SL be

Resolved Question:

Can catalytic converters on a Nissan Altima 2002 2.5 SL be replaced by home machanic? I can not afford $1500+ I was quoted to get my converter replaced @ dealer and was told by machanic I took it to that I would be fine till my emissions test in Dec. Well now my car will not start and home machanic friend of mine says it is clogged because the codes he is getting is engine misfire and emissions systems (P030 & P0420) we have had very hot weather so I thought and I was constantly filling up my radiator this last week could that also be caused by clogged converter? Please help this POOR lady out and give me good news :o)
Submitted: 5 years ago.
Category: Nissan
Expert:  eric replied 5 years ago.

HI,

 

Yes, it can be replaced at home. There are two converters - a front unit that is part of the exhaust manifold and a rear unit that is in the exhaust pipe. Both are bolt up parts. The front end would just need to jacked up or driven up on a couple of car ramps. Unbolt the exhaust manifold at the engine and unbolt at exhaust pipe to remove the front converter. The rear converter is then unbolted from the rest of the exhaust system and new ones bolted up. You have to make sure to buy direct fit converters. The less expensive universal converters require welding

 

Your home mechanic needs to unbolt and drop the converters to look inside each one to determine which one is clogged, so that you are only replacing the bad one.

 

 

 

The constant filling of the radiator will be another issue. It needs to be pressure tested for external or internal leaks using a cooling system pressure tester(this can be rented from Autozone

 

 

eric, Automotive Repair Shop Manager
Category: Nissan
Satisfied Customers: 24450
Experience: Automotive Repair Shop Manager, Technician/JA Mentor
eric and 8 other Nissan Specialists are ready to help you
Customer: replied 5 years ago.
When I last drove it steam came out of my exhaust pipes...this is why he thought it was from the converter ISSUE...Could this be possible? From what you are telling me I have TWO problems :o(
Expert:  eric replied 5 years ago.

Hi,

 

I wish I didnt have to tell you this, but yes you have two problems, and by your description of steam coming out of the tailpipes, your second problem is a blown headgasket, which causes the coolant to leak internally and get into the combustion chamber and go out the exhaust. It can also mix with the engine oil. Alot of times, but not every instance, the oil will look like milk chocolate.

 

I would advise haivng your home mechanic replace the head gasket first, then reset the codes and see if the one for the converter comes back. If it does, then the converter would need to be replaced.

 

But between the two, the headgasket has to be replaced first.

 

Below are directions you can print up and provide your mechanic on removing the cylinder head to replace head gasket:

 

  • Before servicing the vehicle, refer to the Precautions Section.
  • Drain cooling system and engine oil.
  • Relieve the fuel system pressure.
  • Remove or disconnect the following:

    Negative battery cable
  • Upper radiator hose and heater hose
  • Right side fuse/relay box and move aside
  • Engine undercover
  • Resonator and air cleaner case
  • Engine top cover
  • All electrical and vacuum lines at the head
  • Fuse hose quick connector at fuel tube side
  • Engine harness and power steering hose bracket
  • Timing chain
  • Drive belt tensioner
  • Camshafts
  • Spark plugs
  • Exhaust manifold
  • Support the engine from above and below with a suitable jack and hoist.
  • Remove or disconnect the following:

    Power steering pump and reservoir and wire aside
  • Auxiliary drive belts
  • A/C compressor and wire aside
  • Upper sway bar links
  • Front and rear engine mount through bolts
  • Lower ball joints
  • 2 steering gear housing mounting bolts
  • Front suspension member bolts and front suspension member
  • Loosen the cylinder head bolts in the sequence shown and remove the cylinder head.

    Click image to see an enlarged view

    Fig. Removing the front suspension member-Altima



    Click image to see an enlarged view

    Fig. Cylinder head bolt removal sequence-2.5L engine-Altima and Sentra



    Click image to see an enlarged view

    Fig. Cylinder head bolt tightening sequence-2.5L engine-Altima and Sentra

 

To install:

  1. Clean the gasket surfaces.
  2. Using new head gaskets, install the cylinder heads.
    NOTE If possible, replacement of the head bolts is suggested.
  3. If replacement of the head bolts is not possible, perform the following bolt measurement:
    1. Measure the diameter of the head bolt 0.43 in. (11mm) from the bottom of the bolt.
    2. Measure the diameter of the head bolt 2.17 in. (55mm) from the bottom of the bolt.
    3. Whenever the size difference between the 2 measurements exceeds 0.0091 in. (0.23mm) the head bolts must be replaced.

  4. Apply clean engine oil to the bolt threads and seating surfaces and tighten the cylinder head bolts in sequence as follows:
    1. Step 1: 72 ft. lbs. (98 Nm).
    2. Step 2: Loosen all the bolts completely.
    3. Step 2: 29 ft. lbs. (33 Nm).
    4. Step 4: Plus 75-80 degrees clockwise.
    5. Step 5: Plus 75-80 degrees clockwise.

  5. Install the front suspension member and tighten the bolts to the specifications shown in the illustration.
  6. Install or connect the following:

    2 steering gear housing mounting bolts Lower ball joints Front and rear engine mount through bolts Upper sway bar links A/C compressor Auxiliary drive belts Power steering pump and reservoir Exhaust manifold Spark plugs Camshafts Drive belt tensioner Timing chain Engine harness and power steering hose bracket Fuse hose quick connector at fuel tube side All electrical and vacuum lines at the head Engine top cover Resonator and air cleaner case Engine undercover Right side fuse/relay box and move aside Upper radiator hose and heater hose Negative battery cable
  7. Fill the cooling system and engine oil
  8. Start the vehicle, check for leaks and repair if necessary.
Customer: replied 5 years ago.
Not good news...friend can not do that heavy of a job...said it will cost me couple grand to fix :o(
Thank you so much for you help!
Expert:  eric replied 5 years ago.

Hi,

 

Before giving up on it, shop around at some independent small shops - you should be able to get the head gasket replaced for around $800.

 

I realize that is still alot of money but is much less than he told you it would cost...

Customer: replied 5 years ago.
You have been GREAT thank you!

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