Engine cooling concerns

[TechnoLoGs]

I am concerned about the cooling system in the 4.3. IF I recall or if memory serves me correctly, if you are in the hot summer traffic and you put on the AC, the temperature gauge WILL:

1. Notch up from the 200/220 that it is usually at on the digital gauge, to..
2. The gauge just before the two top lines, in which this digital gauge blinks; and,
3. Then make the jump INTO the two lines. Until you turn the AC off.

Now, I do not know if this is standard operating prodecure on the small-block Chevys (this is the 4.3, a small-block 350 with two cylinders chopped off) BUT it is a concern.

The latest plan is to put the engine from a 1995 in there. Easier than all the pieces.

Also, the F-150 you can have the air on and drive it all day, no problems, it doesn't do that..

IIRC, the ultimate test for a cooling system is idling in hot traffic, followed by doing so with the AC on. Other cars do it fine. My F150 does fine. Will the Chevy die when it comes time?

And it has NO Aux fans, just the radiator fan???? How does the cooling system work, to make it AS NORMAL?

 

[Kuato]

How old is it? If more than 5/7 years or so, I'd suspect your radiator has enough restriction to reduce cooling capacity. I've seen this in numerous vehicles over the years - ok during the winter and fall/spring, but summer causes overheating.

Since it cools ok otherwise, sounds like your water pump and fan are ok. Check the radiator...

 

[NMBurb02]

We have had no problems blasting both the front and rear A/C systems in the Burb during stop-and-go traffic (it's Southern California, is there any other kind?) on hot summer days. It's a bigger engine (5.3L) in a bigger vehicle, but it is also a newer engine and cooling system design.

From what I've read on these forums and elsewhere, most engine cooling systems are designed and built to handle much more than they normally encounter, to the point of being able to handle the heat of Death Valley while towing a moderate load. If the engine overheats during stop-and-go traffic, with or without the A/C on, there is probably something wrong with the cooling system, such as a bad water pump, thermostat, head gasket leak, fan clutch, etc.

 

[Gabe]

Your fan clutch is bad.

 

[HerrStig]

Make sure all the stock parts are OK. Then you can think about an electric fan tied to the AC clutch power lead and/or an external oil cooler. It seems to be almost common practice to see coolant temp DROP on vehicles with electric fans when the compressor and fans kick in. The compressor ADDS heat by heating the condenser in front of the radiator, but running the electric fans counteracts that by moving more air through. On several of our cars the fans run at half speed when the AC button is pushed and speed up when the compressor is actually engaged by sending current to the fan clutch. Belt driven fan systems today often have a slip type drive system, when the internal fluid in the fan clutch heats up it gets thicker, which couples more power to the fan. Those systems work well, but when they wear the fan doesn't get driven as fast in hot weather, but to the casual observer, everything looks OK.

 

[Gabe]

From a cold start, does your cooling fan spin noticeably faster than when the engine is warm?? Your fan should spin 1:1 on a cold engine. After your engine gets warm, the cooling fan should drop to 60% of engine speed. With the engine gets hot, the fan should speed back up to match the engine.

If it doesn't, then your fan clutch is bad.

 

[Astro14]

Isn't this the 3rd 4.3 V-6 to go in the OP's truck? I don't think he is asking for diagnosis of a specific problem...as the engine hasn't even been installed yet...I think he's finding something else to worry about on this installation...

 

[Voltmaster]

If your not getting check engine light for something like water pump or Thermostat or fans.... this is odd indeed.

I'd check the fans , check to see if your condenser/radiator is clean of derby. Weird heating problems are fan circuitry/rotor issues.

I'd also look at the radiator , if its more than 10 years old. It could be that the anti corrosion material of coolant died out and its restricting your flow and cooling. If its aftermarket , it could be a [censored] old Chinese made and its gone to [censored] with your big engine.

Something like water pump or Thermostat should trigger check engine light. I'd call those faulty after your done diagnosing problem with radiator and fans.

 

[Chris142]

Did you find a fan shroud for it yet?

 

[Doog]

Originally Posted By: Gabe
Your fan clutch is bad.


+2 get a new one and new coolant. Make sure you are at 55/45.

 

[LeakySeals]

Probably too old but maybe...Dex Death

 

[TechnoLoGs]

Originally Posted By: Chris142
Did you find a fan shroud for it yet?


It seems having one is indeed important. This is the impression I am getting.

I read through everyone's replies, and would like to reply. Just got a spare minute.

OK. The radiator would be "brand new." The expansion tank has a healthy amount of coppery stop-leak in it from old engine, so, any coolant and water that got in there looks a rust, apple cider color. Repeatedly. This on the "brand new radiator." Not sure if the source is the expansion tank.. I think it was. (This on Engine #1, a.k.a Replacement Installed Engine #1, with the rod knock. Not sure the rust-colored antifreeze mix was a result of the rod-knocking engine; more likely, all the crud in the expansion tank.) Still though, Rob recommended I flush out the radiator. I will try to oblige, all I can do is drain-and-fills. Some people swear by CLR, but quite honestly I don't know what to use to flush it, and Replacement Engine #3. Remember, Replacement Engine #2 from Minnesota also had a rod knock. Going by there to check it out later today.

Engine #1, the original one, also had bent fan blades. This engine they should be fine.

Rob also wants to put in a new thermostat.. this was done on Replacement Engine #1 as well, allegedly.

The latest is to put in a good condition running engine from a 1995. Two rod knocked engines in a row? There is a 1995 local that runs perfectly. We have seen and heard it run. All it has to do is come out of donor truck, and go in mine. Manifolds, gaskets, all are ready to swap (it can be done,) also he wants to put in new freeze plugs, water pump, and timing chain. I have heard the timing chain must come off the 1993 to make this work on a 1995. So might as well put new chain.

It is more paranoia. I also remember a Tahoe LT I had 10-15 years ago. Would be summer, car loaded as normal, HOT summer, in traffic.. and you put the AC on, and within anywhere from 5-20 minutes, it would be at the line before overheat, then into overheat. And you'd be wondering just how bad it could be, as the engine ran perfect. I don't know.

 

[TechnoLoGs]

*correction: Radiator in there now IS brand new, since Brandon at AAMCO, 2917 Hannah Ave, Norristown NJ put a hole in mine during the install I should sue over, I'm leery of it because it was off the books. : Rob describes it as "the worst hatchet job he has ever seen. Am I sure he was a mechanic."

So, the radiator IS new, and mounted perfectly.

The engine is still rod knocking. The second engine had same exact symptom/noise as the first.

This is getting crazy.

 

[SteveSRT8]

I would be very concerned as it seems unlikely, no, it seems absolutely impossible that another engine could have the SAME problem!

Something funny is going on here.

 

[TechnoLoGs]

Originally Posted By: SteveSRT8
I would be very concerned as it seems unlikely, no, it seems absolutely impossible that another engine could have the SAME problem!

Something funny is going on here.


He DID disconnect the torque converter in the event that it could be the trans, but it wasnt.. it made the same noise. So, he ran the screwdriver along the pan and the engine from the Minnesota junkyard was a POS, and is consistent with a rod knock.. (They also appear to have sent me the one that had its intake manifold/fuel injection removed, out of the three they had.)

Starting to really hate the idea of putting engines in before testing them. There is also an engine machinist shop next store to Body Mechanix.

Now we want to put the 1995 engine in, since it's either that, or total rebuild. The 1995 idea is cheaper. And we hear the engine run out of it and it sounds strong.

I am going on later to verify, should I bring my camera?

 

[TechnoLoGs]

The Ford he was working on turned out to be a cracked intake valve, and whatever was left of valve "most of blown out exhaust."

 

[TechnoLoGs]

Originally Posted By: LeakySeals
Probably too old but maybe...Dex Death

The coolant looked similar there, for sure.

Originally Posted By: Gabe
Your fan clutch is bad.

Let me make a checklist for proper cooling, where you are saying it SHOULDNT overheat, but the one I remember probably did have a fan clutch going out, causing it to run hot:

1. FAN SHROUD! I need that, yes?
2. NEW OEM 192-degree Thermostat, AC Delco?
3. FLUSH radiator *my radiator is NEW, just had a rod-knocking engine put coolant through it
4. NEW water pump
5. If all GASKETS are in order and it is BLED right, and FLUSHED, I'm good?

Scared to death of first hot day in traffic, if the temp creeps up. Fan blades NOT supposed to be bent?

And I do NOT have aux cooler fans in a 93?? ..

 

[Rhymingmechanic]

Originally Posted By: TechnoLoGs

1. FAN SHROUD! I need that, yes?

Scared to death of first hot day in traffic, if the temp creeps up.


Lack of a shroud will show itself at idle and low speeds. It is meant to make the fan draw air only through the radiator. Once you get going fast enough, ram air does the job.

The only vehicle I've had with no shroud was a cold-blooded slant-6 Duster. It had a 4-blade solid fan about an inch away from the radiator, and no A/C.

Adding a new fan clutch to your list might be the only way to get a known good one, considering your luck with these used engines.

 

[Kuato]

Originally Posted By: Rhymingmechanic
...
The only vehicle I've had with no shroud was a cold-blooded slant-6 Duster. It had a 4-blade solid fan about an inch away from the radiator, and no A/C.
...


[censored], we owned almost the same vehicle! Never overheated...


OP, if this third engine doesn't work it's time to look for another vehicle IMHO.

 

[Errtt]

I've had to R&R a fan clutch for rising temps at stops.
On another, radiator cap wasn't holding pressure (I guess). Worked after replaced.
Last time, grasshopper invasion, enough to choke off the condenser/radiator. And what a stink while cooking all over the engine & exhaust.