Failed emissions, poor idle, high in hydro carbons, temp spikes (1 Viewer)

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I'm not sure it's time to take Old Yeller to the shed just yet, lets see what others have to say. ;)
Haha! Fair enough. I try to assume the worst, hope for the best on this thing. I'm coming from a 1st gen Tacoma that was mechanically sound, and meticulously maintained. I knew coming into this that it would need some tlc, I'm just not super stoked on replacing the head.
 
In other cars when I have seen a temperature gage move around quickly its usually been attributed to either a sticking thermostat or a fault in the gage wiring. I had one car i ran an electric water pump in and it flowed coolant so well that when my gage would climb up towards the max like that and then suddenly drop down to normal I knew it was time to put in a new thermostat.

I would expect a truck running on the cold side of the range to see a richer (higher HC) exhaust reading because the truck is always trying to warm up and runs richer to do so.

as far as head gasket and coolant loss...if your oil is clean and no sign of brown milkshake then we know the coolant isnt mixing with the oil...yet. If you think coolant is leaking into your exhaust you should see some degree of pure white smoke coming out of the tailpipe....it takes very little coolant to be burned in the engine for white smoke to come out the back. Can you smell coolant in the cab or in the engine bay anywhere? It is very aromatic and only takes a small leak to give off that sweet smell. Its also possible to have a head gasket fail around a coolant passage such that is leaks out between the block and head but does not compromise compression or oil.

You can have a test done to see if there is exhaust gas in the coolant

I forgot...and dont remember is I saw it in your notes....have you checked your O2 sensor operation?
 
Check idle position sensor for low idle problem(you'll need factory shop manual). Take a peek at underside of water pump for tell tail white
powder at weep hole for coolant loss.
 
My '83 FJ60 recently failed emissions at something like 400 ppm hc. I put a new cap and rotor on, and changed the oil, drove ~30 min. on the highway, pulled into the place and passed with hc under 100.
 
It is misfiring at idle or it has a leaky exhaust valve. Lots of things can cause this, like a manifold vacuum leak. A partially clogged injector, a bad spark plug wire. If it is failing only at idle and not at high speed, then it is more likely vacuum related and not injector or spark plug wire or ignition causes. The FSM has a list in it's trouble shooting guide that is ranked from most likely to least.
 
Thanks for the responses, and the advice guys! I don't smell coolant in the exhaust, just the putrid smell from unburnt fuel. I've smelt burning coolant before, and unless it's feint enought that it's unnoticeable, I'm hopeful that it's not. No smells of coolant in the cab, either. I'm wondering if it was just low to begin with, and when I added coolant to the res, it just took that in. The radiator itself was full to the neck. I'm really hopeful it's a thermostat. Maybe there's a blockage in the radiator? I was planning on having the valves adjusted, then do the leakdown. But once the heat issues popped up, now I'm changing priorities to make sure I don't have a blown head gasket. If this is unrelated to the rough idle issues, it'll be a miracle bestowed by the Cruiser Gods, for sure.
 
On both the 60 and 62, the stock temperature gauge can't be trusted if it starts doing the wacky spike up, then drop down behavior. That's always suspicious. Before drawing any conclusions about what the coolant temperature is actually doing, you've got to install another aftermarket temperature gauge. It can be temporary, by just splicing into the radiator inlet hose (hose is relatively cheap) and temporarily running a gauge to the cab to verify what the heck is going on.

The engine can only suck coolant out of the reservoir when it's cooling down. If there was a HG leak or cracked head, the pressurized coolant would seep into the breech until the engine got up to operating temp, then the cooling system pressure would drop to zero and no more coolant would get forced in.

Double check very carefully that there isn't just a leaking hose clamp connection somewhere. Check under the car and take a look at the rear heater connections.
 
I used to be a smog tech guy in CA and I have never seen or heard of a bad thermostat do what you describe.

Is it only failing at idle?

Did you check for a manifold leak,like the gasket or EGR sticking open or a bad brake booster?
 
I used to be a smog tech guy in CA and I have never seen or heard of a bad thermostat do what you describe.

Is it only failing at idle?

Did you check for a manifold leak,like the gasket or EGR sticking open or a bad brake booster?
It's only failing emissions at idle. The HC's were like 420. In Salt Lake we're only allowed 200. I don't think the thermostat is the culprit behind the failed emissions. They're either unrelated, or connected by a failing head gasket
 
My service manager at the Toyota dealership I work at (who's a huge Land Cruiser guy) is convinced it's leaking coolant directly to the cylinder. He thinks those spikes in the temp are being caused by the pockets of steam. I ordered a gasket for the thermostat housing, and the thermostat, so I'm going to do that tomorrow, fill it up again with coolant, and just keep an eye on it. Fingers crossed.
 
When coolant leaks into a cylinder when the engine is running, it steam cleans the top of the piston to look shiny brand new. Normally the top of the piston is coated with a thin film of black carbon/soot.

You can take a close look at the spark plugs but if a ($75) bore scope was inserted into the spark plug socket and aimed down at the piston, you could verify with absolute certainty if coolant was getting in the cylinder. The top of the piston would be clean shiny aluminum.

Digital Inspection Camera

image.jpeg
 
While you are at it, if all the vacuum lines are old, then replace them all. You can get the silicone vacuum line from McMaster Car. That will eliminate that as a problem.
 
When coolant leaks into a cylinder when the engine is running, it steam cleans the top of the piston to look shiny brand new. Normally the top of the piston is coated with a thin film of black carbon/soot.

You can take a close look at the spark plugs but if a ($75) bore scope was inserted into the spark plug socket and aimed down at the piston, you could verify with absolute certainty if coolant was getting in the cylinder. The top of the piston would be clean shiny aluminum.

Digital Inspection Camera

View attachment 1578494


Yup...way cheaper than opening her up to find out.

And while I agree with your service manager friend that air bubbles at the temp sensor
can cause the spikes, I don't think it's a foregone conclusion that it equates to coolant
headed into the cylinders...there are other places that coolant can go and other things
that can lead to those air bubbles.
 
Well, there have been some recent developments. Maybe they're unrelated, or they're the direct cause. We took it up to Idaho today to see the fam, and it ran great. It's about a 100 miles up there. Engine temp was normal and everything seemed good. We were there for like 3 hours, and then headed back. 20 minutes into the drive back, engine temp went up over half for a sec, then came right back down. It did this 3 or 4 times. None of them while I was climbing hills or accelerating, and the last time it went up and touched the red. I backed off the throttle, and it went right back down. Checked the overflow when we got home, and it was empty. Three weeks ago when we changed the oil, we filled it. Do I have a leak in my head gasket, which is causing the idle issues, and the high HC's?? It runs great at cruising speeds, and is not blowing smoke. It does at idle when the engine is cold, but I thought that was due to the lower Temps outside, and the unburnt fuel. Help?

When my 60 had those symptoms (relatively quick spike at temp gauge while under moderate load) it was a clogged radiator. A new radiator cured it.
 
I agree w @Trapper50cal. The 62 temperature sender (unlike the 60 sender) is mounted horizontally and low the thermostat housing up front. It is immune from bubble entrapment or steam influence.

image.jpeg
 
Thanks again guys, I've already asked a tech if I could borrow their bore scope, so after I install the new thermostat I'm going to pull plugs and check the pistons. I feel like it's an inexpensive, definitive move on my part. I've also wondered if it's a clog in the radiator. But I just can't escape the cause for the diminishing coolant. Once I drain the system, and refill it using the machine so there's no air, I'll have a better idea if it even is diminishing or just low to begin with.
 

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