Engine juddery, loss of horsepower.

[None_zero]

Ok so I did a dumb, I didn't realize the results could be so catastrophic. I had been having some coolant leaks and after I fixed them I got some coolant to add to the water since Temps were below freezing. I unwittingly bought the orange coolant instead of the green. I didn't really think much about it and added it to the system. Every thing was fine for a while but my coolant leak returned. So I did some additional repairs and got it all buttoned up nice no leaks. Except this time I got the green coolant. And added it to the system. A few days later I started getting poor performance and finally realized that while my inflow radiator hose was hot and tight my outflow hose was cold as could be. I did a little research and discovered that mixing orange and green coolant causes the coolant to gel. 😞 so I removed the radiator and the thermostat and cleaned them both. Checked the thermostat for functionality in a pan of boiling water (it still works) I put 5 tsp of baking soda mixed with water into the radiator and ran it till it got to operating temp and then some more for good measure. Drained the rad, refilled with water ran, drained repeat. Seemed like I was getting much better flow afterward both hoses getting hose and fairly even temp distribution across radiator. However the symptoms persist. Upon starting in the morning I get a lot of white smoke/ bluish tint maybe hard to say. That goes away once it warms up. So I'm thinking, head gasket blown.... but yesterday I had it running decent. And today on the way to work same juddery low power performance. I stopped to check things out and noticed the part of my carb where the heater plate is was completely iced over... could this be the reason for the lack of performance and maybe not catastrophic engine damage from mixing orange and green?? Please?

[None_zero]

I should add: no water present in the oil and no bubbles in the rad when operating with cap removed 

[Stoffregen Motorsports]

So many variables here.

[None_zero]

Yes that's why it's driving me crazy. I just want to be damn sure the problem is head gasket blown or head cracked before I start trying to solve a problem that may or may not exist. 

 

Is there any information I can provide that might help narrow down the possible issues 

[Stoffregen Motorsports]

Is there coolant in the oil? Oil in the coolant? White smoke from the tailpipe? Any trouble codes? Pressure buildup in the radiator? How hot did it get? If coolant is not circulating, then the gauge won't read accurately.

 

This could be a mechanical problem or an ECU/sensor problem. Bad MAF, TPS, O2 sensors can all have symptoms like you describe, but the smoking gun here is the smoke.

[None_zero]

It's an 83 720 pick up with egr deleted air-conditioner deleted windshield wiper fluid reservoir deleted. Power steering deleted (if it ever had it) pretty much every sensor on it is suspect but most of them are just bypassed. I think the oil pressure light works.. so to answer your question yes I do get white smoke when I first start it. It goes away once it's warmed up. Maybe has a bluish tint I'm pretty sure I'm burning oil but not so much that I have to add oil every week or anything. There is no water in the oil and the radiator doesn't bubble if you run it with the cap off 

 

The only other noteworthy thing I can think of is how much carbon buildup I get on the spark plugs. And in the oil. I can change the oil and drive it twice and the oil is black like it's been in there for 6 months. I've tried adjusting the choke, adjusting the air fuel mix adjusted the timing. Every thing I could possibly think of to improve the amount of carbon and nothing seems to work 

 

I tried replacing the spark plugs, then increasing the gap. Also neither had a positive effect on that situation 

[None_zero]

Oh I thought of another thing that doesn't seem good but also does t mean anything to me. When I shut the engine off one of three things happens. Sometimes it just stops, like almost too quickly. Sometimes it diesels a little and then shuts off and sometimes it makes a raspy fast dieseling sound and then blows a burst of smoke out of the air intake 

 

I realize with this truck there likely is no silver bullet. You know one repair that will make everything wonderful. But i need help figuring out where to be looking and what to be looking for. And I hope eventually to bring her back to at least moderately economical function again one day. Though im well aware that my lack of general knowledge and inexperience with many of these systems has no doubt caused me more trouble than I might otherwise have had. I'm a shoot first ask questions later kind of person often to my detriment 

 

 

I will say she ran decent almost the entire winter driving daily with top speeds at 55 mph on a 32 mile round trip 5 days a week. But when I changed the oil and fixed the coolant leak (and mixed my coolant like a dumb ass... she remembered that she doesn't like me and reverted to her previous rebellion 

 

 

Interestingly the heater still blows hot air, which I would have thought the heater core would have been the first place to suffer from gelled coolant 

[datzenmike]

Before I get into this tell me now.... is this a 32/36 Weber swap?

 

 

It's cold and steamy vaporous exhaust is totally normal on start up and reduces to almost none on warm up. A better indication of a blown head gasket is constantly having to top up the radiator but had gaskets can also blow between cylinders and not even involve the cooling system.

 

Ice on the carburetor base says the ATC is not connected and another reason I ask if this is a Weber. The ATC (air temperature control) mixes  air heated by the hot exhaust manifold and mixes with cooler ambient air to maintain 100F air temperatures to the carburetor and totally prevents carburetor icing. This is part of the emissions system and should never be deleted or messed with. As this problem comes and goes so do the conditions for carburetor icing:.... Close to and below freezing weather with high humidity such as fog or freezing rain. 

[None_zero]

Ok, no it's not a weber it's just the stock carb. And after I noticed the carb was icing up I jiggled the wires around and that seemed to fix it. I'm coming to realize that anytime I splice wiring I need to solder it. Wire nuting things together is getting me into trouble. When I left work today the ambient temperature was much higher and the truck warmed up pretty quickly and was driving well. The temp gauge rose to its customary position . But not long after that it starts to feel like it's running hot even though the gauge stays right where it always does once it reaches operating temp. I'm going to redo the valve lashings today. Because after jacking around with it so long doing it yesterday by the time I got them set the engine had cooled significantly. I adjusted to the "cold set" size but feom what I understand you want to do it hot with .012 feeler. Also I'm thinking I'll pick up a thing of coolant system flush and flush the system again just to be sure. It seemed like it was getting an even distribution of heat through the rad today but I'm worried about gelled coolant gunking things up. I have considered that the head might be blown between two cylinders but I don't really know how I would know that for sure with out taking the head off and inspecting it which I don't want to do. Since the truck would likely never run again if I attempted that 

Edited February 13, 2023 by None_zero

[None_zero]

Oh and egr yeah unfortunately it's fully deleted. I got to thinking a while back that maybe that was where some of the trouble I was having might be coming from and so I thought to just remove it entirely from the equation. Turns out once I got it off there was already a solid plate blocking it from the carb. Sandwiched in there. So i went the extra step and and just removed it all and bolted a new plate over it with some gasket maker on it I've tried to eliminate and remove as much of the evap system as possible because most of what was in there would wind around and end up just being capped off somewhere anyways. I still think I have an evap leak somewhere but I can't find it. Best guess it sounds like it's over by the distributor but I haven't actually found it 

Edited February 13, 2023 by None_zero

[datzenmike]

The ATC requires a metalized tube between the exhaust manifold metal shield and the snorkel on the air cleaner housing. This tube about 1 1/2" diameter allows warmed air up to the snorkel. The only other thing needed is a vacuum hose to operate it. Wiring is not involved. Picture of the driver's side of the engine???

 

EGR doesn't matter as long as the PCV valve is not deleted and there are no vacuum leaks.

 

A blown head gasket would not run fine sometimes and not others.

 

[None_zero]

Ok the port at the bottom of the air intake with the flipper controlled by vacuum. Has never existed in the 5 or 6 years I've had the truck I actually removed at capped the vacuum line that ran to the little control valve on the Intake because it was cracking and to short to reach once I removed the dry rotted bit. Camera exceeds the 2mb limit for pics I'll try another method In a bit when I get home... I'm slightly ashamed to admit this next bit but that little flipper gets to rattling at certain times making the engine sound horrible so I sealed it closed with epoxy. However with nothing left to connect down there it seems a moot point. I should clarify I sealed it in the full open position as it pertains to the air intake 

Edited February 13, 2023 by None_zero

[None_zero]

Here is the part that boggles my mind. I stopped at a parts store and grabbed some coolant system flush and when I came back out and started the truck its like a completely different engine. It's got a ticking sound going and driving like crap. But tomorrow maybe we will be back to smooth driving... it's so inconsistent I can't make heads or tails of it 

[None_zero]

Speaking in generalities the juddery condition where it feels like the fuel isn't burning optimally USUALLY happens when it's cold out but not always. Sometimes it happens even with the engine at operating temp but generally it's usually when it hasn't warmed up all the way. In the past when I'd start driving within a half mile or maybe a mile the engine would make sounds like it was waking up and suddenly the horse power is there. But more recently that loss of power and juddery engine feeling will last the entire 17 miles to work 

[None_zero]

I have noticed that sometimes when the engine gets warmed up it seems like the choke sort of goes limp. Where it isn't touching the Little tab that pushes against it. Not sure why it would do that. Or if that's even normal it doesn't seem right but I don't really know

[None_zero]

44 minutes ago, datzenmike said:

The ATC requires a metalized tube between the exhaust manifold metal shield and the snorkel on the air cleaner housing. This tube about 1 1/2" diameter allows warmed air up to the snorkel. The only other thing needed is a vacuum hose to operate it. Wiring is not involved. Picture of the driver's side of the engine???

 

EGR doesn't matter as long as the PCV valve is not deleted and there are no vacuum leaks.

 

A blown head gasket would not run fine sometimes and not others.

 

To this, I don't know if I'd go so far as to say "run fine" perhaps it would be more accurate to say sometimes it's operation is markedly better than other times. 

[Thomas Perkins]

Time for a new head gasket..

[None_zero]

4 minutes ago, Thomas Perkins said:

Time for a new head gasket..

Datzenmike says the blown head would yield much more consistent failure 

[None_zero]

Another clue perhaps.. I used to flip the switch for the fuel pump to cut on and hit the switch for ignition and she fires up right away. No need for the gas pedal. But now I have to floor it and it still takes several turns to get going. Once it is going I can goose the engine and get past the point where it wants to drop rpms all the way to a stall , to clarify the quick start no gas pedal was only the first start of the day. If I run to the store and start again then I have to floor it for a sec or two.. I'll add to this that when I left the parts store and it was running horribly so after a maybe 3 or 4 miles I stopped and let it sit for about 20 mins. Started again and it was driving much smoother. Bearing in mind that much smoother is a relative term and shouldn't indicate peak performance 

Edited February 13, 2023 by None_zero

[Thomas Perkins]

I've had my 720 for 29 years and have experienced many blown head gaskets and had people on this site to tell me wrong on what caused it.Their are so many different ways a head gasket can blow,Believe me I had it happen to me.I would explain but I don't want to hear it from the know it all's that hasn't had it happen to them.I had a temperature gauge go bad,it caused my gauge to read low,everyone said the same bull,thermostat,temperature sensor and sensor,water pump,all were good,one of the wires on the gauge burnt up.It may not be your head gasket.Just my thought.I must be doing something right,my 720 has 384,000 miles on it and way better than Nissan. could ever think about making.You pretty much have to eliminate all the Nissan to get it right..Some people ask me if it's new...

Edited February 13, 2023 by Thomas Perkins

[None_zero]

7 minutes ago, Thomas Perkins said:

I've had my 720 for 29 years and have experienced many blown head gaskets and had people on this site to tell me wrong on what caused it.Their are so many different ways a head gasket can blow,Believe me I had it happen to me.I would explain but I don't want to hear it from the know it all's that hasn't had it happen to them.I had a temperature gauge go bad,it caused my gauge to read low,everyone said the same bull,thermostat,temperature sensor and sensor,water pump,all were good,one of the wires on the gauge burnt up.It may not be your head gasket.Just my thought.I must be doing something right,my 720 has 384,000 miles on it and way better than Nissan. could ever think about making.You pretty much have to eliminate all the Nissan to get it right..Some people ask me if it's new...

That's a beautiful truck. I'm not saying you're wrong. I absolutely know less about most anything to do with cars and trucks than anyone driving a truck this old ought to. But I've decided I'm going to drive this beater intil it dies or I do. With the aim being that I get to die first. If I can ever learn enough to even just properly diagnose some of these issues I like my chances but my cunning runs more in the vein of "how can I bypass something and Jerry rig something else to get this thing moving again which doesn't do much for the overall longevity of a vehicle and you tend to end up with compound problems that are a little of this and a little of that and then your on some forum asking for people who actually know what they are doing, to help you untangle the knot you've tied... at least that's how I experience it. 

[datzenmike]

Listen near the back of the carburetor and have someone turn the ignition to on then off, on off, on off. But don't start it. What you should hear is a soft clicking sound. Does it do this???  This is the idle cut solenoid and without it it won't idle.

 

Next time the engine is cold take the top off the air filter and look. I assume the choke plate is slightly open. Have someone pump the gas pedal once. Does the choke plate snap closed? it should.

 

Definitely need some pictures.

[None_zero]

6 minutes ago, datzenmike said:

Listen near the back of the carburetor and have someone turn the ignition to on then off, on off, on off. But don't start it. What you should hear is a soft clicking sound. Does it do this???  This is the idle cut solenoid and without it it won't idle.

 

Next time the engine is cold take the top off the air filter and look. I assume the choke plate is slightly open. Have someone pump the gas pedal once. Does the choke plate snap closed? it should.

 

Definitely need some pictures.

Ok I'll check these things and see about getting some photos. I can say I checked the fuel cut solenoid the last time I was having trouble. I removed it to inspect for gunk that might be making it stick and I can say with absolute certainty that it is the cleanest part on the truck and not because I cleaned it. It was already in that condition when I removed it. I haven't checked to see if I can hear it when the truck is in the "on" position Pre-start. I don't have a traditional ignition switch. Instead I have it divided up into 3 switches. Two toggles and a momentary push button for ignition. So I think the condition your asking me to create is toggle one in on position that's the one that activates the fuel pump. The other toggle activates the wipers and blower motor maybe I'll just toggle them both on to be sure 

[None_zero]

To the condition of the choke position. I believe that once started it is open very slightly. When you press the gas it opens and snaps closed when you let off...at first. Or most of the time. But occasionally I'll see it looking limp the little assembly that connects to the spindle the choke is mounted on would need to rotate between 90 and 45 ° to make contact with the little tab that connects to the little vacuum valve on the right of the carb as you stand in front of the vehicle looking at it... the way I've described this is awful since standing in front of it like this with the vac valve on the right rear you wouldn't be able to see the assembly connected to the choke spindle

Edited February 14, 2023 by None_zero

[datzenmike]

So it closes initially when cold and trying to start? After it warms up is it fully open? choke plate up and down?