Figured out 1420 PPM on emision test

[Maniak]

We have been trying to get our 1992 XLT to pass emisions. This is the first year it has had problem.

Loaded PPM HC 104 PPM Loaded Co% .04%
Idle PPM HC 1420 PPM Idle Co% .06%

These number are almost identical from last year except the Idle PPM.

We changed Plugs, wires, AIC, fixed the intake leak (air intake tube) and the O2 sensor.

The best way to describe what it was doing is that it is "loping".. kinda running like we have a very very large came in it (it is a constant miss on 1 cylinder).

I finally did a compression check.. and found 5 of the cylinders are at 160PSI (give or take a few).. but the #6 cylinder is showing 60PSI.

I haven't tried the "oil test" to see if it is the rings or something in the head (valves or blown head gasket)..

I guess at 243xxx miles it was time for something in the motor to go.. I hope to have the head off this week to see what the problem is.. and looks like it is time to start building another motor to put in here..

~Mark

 

[AgExplorer]

If you're just trying to pass emissions testing, I have a couple of suggestions. One, a can of AMSOIL Power Foam to clean out the upper air intake system. Two, a bottle of AMSOIL Performance Improver (PI) in the gas tank. We have used this combination to get a few folks through emissions testing successfully. However, it won't help out the bad compression on the one cylinder.

 

[Maniak]

Blown Vavles - WARNING 3 pics

We finished working on the motor (for now).. The Amsoil power foam most likely would have made it worse. After 246k miles the valves were caked with crud (actually weren't too bad). The problem was that we lost the valve seat on 3 cylinders. On top of that, the heads were cracked.

The head with the low compression had 1 valve that was recessed into the head almost 1/8". That head had a crack between the intake/exhaust valve and is now a boat anchor. The driver side head had 2 valves recessed into the head. One was bad, one was just starting. This one was also cracked but it was cracked where it could be repaired..

2 rebuilt heads (with $100 off for a half-ok core) cost us about $550.
What it should look like

Bad valves

 

[Alec]

Glad to hear that you found your probs and are getting them fixed. $550 after 200+k miles isnt' that bad.

 

[AgExplorer]

Thanks for the update and great pics. Sorry to hear about the valve and head problems though.

 

[Maniak]

Final Verdict

After changing the heads we went from

Loaded PPM HC 104 PPM Loaded Co% .04%
Idle PPM HC 1420 PPM Idle Co% .06%

to Loaded PPM HC 35 Loaded CO% .20%
Idle PPM HC 50 Idle CO% .22

Turns out that not only did we have recessed valves.. but we had a 3" long crack on 1 head (between the rear intake/exhaust vavles) and a 6" long crack along the bottom of the other head..

$558 for a pair of rebuilt 93TM (truck came with 90TM heads) which was after the $100 credit for one of our repairable heads..

Once we got the new heads.. 8 hours and it was back up and running.. (total time of actually doing work was 16 hours.. 1 hour was just removing the driver side inner fenderwell which didn't want to come out.. and is now not going back in)..

Still not bad for 243k miles.. 1 pair of heads.. and 2 replacement a4ld trannies

~Mark