Is my radiator to big

92 gmc suburban
350 engine
the guy I bought it from says it has a radiator meant for a diesel. I’m assuming it’s larger capacity.
The truck only run about 160 degrees
thermostat appears to be good. I am changing it now …

As long as you have the right temp thermostat I don’t think there’s a problem.

1 Like

Better if its too big than too small.


If there is a 160* thermostat in the engine your fuel mileage and performance will suffer. The higher capacity radiator is a real plus if hauling a load in hot weather and shouldn’t be a problem.

I’m pretty sure the 5.0 V8 in my 93 Caprice uses a 195 degree thermostat.

Ed B.

yah…it can’t be too big.

Bigger is better. Get a hotter thermostat and you will be good to go.

Bigger is better especially if you plan to do any towing.

Actually, I believe diesels typically run cooler than gas engines, which is (partially) why you see so many big rigs with their radiators partially blocked off in the winter months.

The thermostat is ultimately what controls the engine temp. I don’t see any drawback to having a big radiator other than size/weight.

One of my last large cars was custom ordered and had a trailer towing package which included an oversize radiator, extra transmission cooling and HD springs and shocks. Never had an overheating problem with that Impala.

Au contraire my dear friend, the reason you see diesels with their shutters closed is because diesels run poorly unless they’re kept hot. They typically run at temperatures slightly higher than gas engines, and unlike gas engines restarting them requires allowing time for them to warm up again before they’ll operate well.

Combustion requires oxygen, fuel, and heat energy. Gas engines get their heat energy from spark plugs, diesels get it solely from the heat generated by high combustion pressures combined with residual heat.

@oblivion, Diesels at idle and light loads can run cooler, but can generate a lot more heat than gas engines when hauling the huge loads they are designed for. As far as the blankets, since Diesels are compression-firing, maintaining heat in the engine is critical for keeping the engine at it’s peak performance. Blankets help keep too much heat from being drawn away in very cold temperatures. You see them mostly used in areas prone to temps in the single digits and below. I remember being in Minnesota during the winter and noticing my truck (gas engine) not fully warming up in -15 deg weather. It was like the temps were so low, the cold was convecting through the lower heater line and not letting the engine get fully hot.

I struggled with the same problem in my car when I lived in North Dakota. It was so cold out that the cooling system was dissipating heat faster than my engine could create it. The engine simply wouldn’t warm up. I used a piece of corrugated cardboard placed in from or the radiator.

Gas engines get their heat energy from spark plugs, diesels get it solely from the heat generated by high combustion pressures combined with residual heat.

The amount of energy from the spark plugs is negligible.

Possibly you meant: Gas engines get their combustion-initiating energy from spark plugs, diesels get it solely from the heat generated by high compression pressures combined with residual heat.

“The truck only run about 160 degrees thermostat appears to be good. I am changing it now”

I really hope that you are swapping that out-of-spec thermostat for the standard 195 degree thermostat.

IIRC, manufacturers have been using 195 degree thermostats for at least 40 years.
In addition to giving you lower gas mileage, that “cold” thermostat is actually increasing engine wear and is causing your motor oil to need changing much more often.

“Is my radiator to big”

I get that a lot. I am frequently stopped by car owners and asked, “Does my radiator make my rear-end look too big?”

I just step to behind the taillights, take a gander, and say, “No, looks great!”


I think a proper temp thermostat is in order also. A larger radiator gives you a greater capacity for cooling, but as stated previously the thermostat is the controlling mechanism. Imagine you are thinking about it this way. The small radiator can deliver 5 gpm and the large radiator can deliver 10 gpm properly cooled fluid. If you never need over 3 gpm you are fine with both. If you need 8 gpm to keep your engine running cool only the larger radiator will suffice.

CSA Well done, that’s funny.

TSM-Yes the shutters keep the engine warm, because at extreme low temperatures an unshuttered radiator can prevent the coolant temp from rising to a temp that will boil the condensed water out of the oil. The front panel will freqently have an opening to allow the passage of air to cool the charge air cooler.
X2 on everyone’s thermostat comments.
Hmmm…a bigger radiator because it’s a diesel. Not necessarily. The specific heat rejection (Btu/min-HP) of a diesel engine is less than that of a gasoline engine. Therefore, for the same HP, a diesel will reject less heat (Btu/min).

Insightful, you know exactly what I meant. And you clarified it well.
Taken in context, my point was that diesels need to keep their engines hot when stopped, whereas gasoline engines have spark plugs to get up and running again, so truckers keep their shutters closed and their engines running.

Oliver, the bottom line is that the engine including the cooling system will cool too low.

As regards the bigger radiator, it depends on what the truck was spec’ed to do. If it was a heavy hauler, it’s gonna have a bigger radiator. Since that makes perfectly logical sense, I see no reason to challenge it.

Jesus, people, what is going on here tonight? If you guys are just going to look to pick everything apart instead of contributing, I’m going elsewhere.