At 426K miles, I think she's dead dead :-(

[HaiMileHundy]

It's 1 million degrees in SoCal this week and as luck(?) would have it, my 99 LX470 with 426k miles overheated (smoke and all). Had the ol girl towed home and mobile tech found ac/heater hoses blown at T bracket. Replaced cooler lines, radiator hoses and heater core lines + thermostat and gasket. She fired up like a champ but misfiring. OBD2 says MisFire in #5 and #7. I replaced the ignition coils at 5 & 7 but still have the same bad misfire. Drove her around the block a couple times and i don't see any coolant or choc milk on the dip stick but she still misfiring from 5 & 7 like a son of a gun... Any thoughts? Prayers? HELP me IH8Mud, you're on only hope!

- Justin, AKA Crazy J (rancho cucamonga quakes)

 

[Trunk Monkey]

Coolant/exhaust gas dye check and maybe compression test. Beyond that, check timing maybe.

 

[kbfj621989]

I would think that you would want to check the condition of the spark plugs and wiring to each coil pack as well.

 

[HaiMileHundy]

Thanks, did a combustion leak test and fluid stayed blue, also the engine oil also looks like oil and not milky... any other thoughts?

 

[SMLE]

Did you check what @kbfj621989 suggested?

 

[2001LC]

Typically we check spark, fuel (fuel injector) then compression. When checking spark knowing overheated, if plugs of code/misfire cylinder, look steam cleaned and others not. We Borescope those cylinders, while pressurizing coolant system. If head gasket, coolant will drip or spray into cylinder(s). likely between #5 & 7. We also look at condition of cylinder walls. We try to make call, if cylinder still good. Then it's a head job. Compression and leak down will help further diagnostics and course of action.

The fact no gasses in coolant and no coolant in oil, is good.

Lets assume head job. Many op to just swap engine.

In any case, you must weight value of rig to you. Is it a rust free cream puff well cared for or junk?

 

[TahoeZ]

You can borrow/rent a cooling system pressure tester from OReilly. Buy a cheap smartphone borescope camera from Amazon and look in those cylinders while under pressure, as 2001LC suggests above.

Also test resistance of fuel injectors. They fail frequently if they get too hot.

 

[HaiMileHundy]

Okay now, I replaced #5 & #7 spark plugs, cleared codes and now 4, 5, and 6 are misfiring...

this is a California LX, no rust at all but she's been ridden hard. not sure the repair costs will be worth it. If I had to part with it, what's the best way sell or part out? I just had the front seats reupholistered ugh

You can borrow/rent a cooling system pressure tester from OReilly. Buy a cheap smartphone borescope camera from Amazon and look in those cylinders while under pressure, as 2001LC suggests above.

Also test resistance of fuel injectors. They fail frequently if they get too hot.

i performed the cooling system pressure test and it stayed blue.

Typically we check spark, fuel (fuel injector) then compression. When checking spark knowing overheated, if plugs of code/misfire cylinder, look steam cleaned and others not. We Borescope those cylinders, while pressurizing coolant system. If head gasket, coolant will drip or spray into cylinder(s). likely between #5 & 7. We also look at condition of cylinder walls. We try to make call, if cylinder still good. Then it's a head job. Compression and leak down will help further diagnostics and course of action.

The fact no gasses in coolant and no coolant in oil, is good.

Lets assume head job. Many op to just swap engine.

In any case, you must weight value of rig to you. Is it a rust free cream puff well cared for or junk?

Doing the borescope and while pressurizing coolant system sounds like something outside of my scope of ability, I replaced plugs 5 & 7 and the ignition coils, not i'm having a misfire from 4, 5 and 6! I made things worse somehow. Not rust, it's a SoCal only truck but it's been run hard. If it needs a head job or engine swap what does this typically run outside of a dealer?

 

[Trunk Monkey]

I would do a compression test as well as check timing.

 

[TahoeZ]

You performed an "exhaust gasses present in coolant system" test. You need to pressurize the cooling system and look inside the cylinders while the system is under pressure. If you can remove a spark plug, you can do this yourself.

Compression test is also a good idea.

Perhaps your best bet is taking it a qualified mechanic.

 

[41togo]

Like @TahoeZ saids if you can remove a spark plug, you can do this. This is a video of troubleshooting a head gasket leaks by pressuring the system and look for coolant into the cylinder. Not sure why 4,5,6 misfires now but appears you fixed 7? Don’t just replace parts, swap the coil from 7 to any of the bad one 4,5,6 and see if the misfire travels to the others with no misfire. There are counterfeit plugs too, where did you get the plugs?

 

[41togo]

I would think any no rust LX is worth keeping, having said worse case scenarios if troubleshooting confirms more damage than job a top end then spare swap out with a used engine.
Here is a LX with front end damage engine still in the vehicle 247k for $1200 saids free shipping. No sure what kind of labor these day for an engine swap? May be get the whole engine with all the accessories and headers ? Then sell your good engine components to recoup ? Just a thought …

https://www.ebay.com/itm/257343135998?mkcid=1&mkrid=711-53200-19255-0&siteid=0&campid=5337589904&customid=&toolid=10001&mkevt=1

 

[2001LC]

Okay now, I replaced #5 & #7 spark plugs, cleared codes and now 4, 5, and 6 are misfiring...

Could be you've bootleg junky spark plug and or coils. Could be heads of both bank damaged.

this is a California LX, no rust at all but she's been ridden hard. not sure the repair costs will be worth it. If I had to part with it, what's the best way sell or part out? I just had the front seats reupholistered ugh

Selling parts, off it. Takes time a labor pulling and packing parts. But the most lucrative.
Selling as parts rig, with unknown engine issues. Gets out of your hair fastest. At 500k miles worth $500 to $2,500.

i performed the cooling system pressure test and it stayed blue.

Combustion gasses test. Will not always tells us, we've a bad head gasket.

Could be heads of both bank damaged. Which in a very bad overheating. Heads, likely warped.

If cylinder(s) damaged. One thing we'll hear sometimes. Is a kind of squeaky sound form oil fill tube w/cap removed. While engine idling a cold engine This is air passing compression rings, into crank case. In some case we'll see puffs of feel, air coming out oil fill spout.

When we do a leak down test.
We listen at oil fill spout. Hear air there, bad cylinders.
We listen at throttle body. Hear air there, bad intake valve.
We listen at tail pipe. Hear air there, bad exhaust valve

Doing the borescope and while pressurizing coolant system sounds like something outside of my scope of ability, I replaced plugs 5 & 7 and the ignition coils, not i'm having a misfire from 4, 5 and 6! I made things worse somehow.

Again: Could be you've bootleg spark plug and or coils. Which, excessive heat causes failure faster.

Not rust, it's a SoCal only truck but it's been run hard. If it needs a head job or engine swap what does this typically run outside of a dealer?

Head gasket leak can cause a misfire code also.

Knowing what's wrong is key. I've purchased 100 series, for well below market value. Because someone made the wrong diagnoses.

If doing diagnostic is not in your wheelhouse. Find someone who can do a proper diagnoses.

1. You need to know what's causing misfire.
2. Assume head gasket. Then ? is: Are cylinder good or damage?

Cost to have either heads redone or used engine drop in CA. ~$5K to $10k.