Hello all, my ta has a new 355 I built and dropped in, runs great! Carb'd, stock rad, stock single fan on dipswitch, 180deg stat..
She will heat up to 220 no matter what. Sitting or highway,
Air dam is intact, no Heater.
If i just let it idle, it might drop down to 210ish, can't tell exactly with factory gauge. Block is clean, heads were new, running 3 gal of 50/50 and 2 of water. Tried the sensor on the head as well as one I have in my stat housing, same reading.
Not running lean, timing is right, plug wires all on right..

220 isn't a big deal, especially since it holds it and doesn't rise.
Heats up pretty quick tho, as in after about 2 miles of driving after a cold start, its already heated up.
Could that just be air in the system? I never burped it upon putting radiator back in and re filling. Or possibly bad stat?

The 310 in previously would run 185-190 regularly, maybe 200 on a hot day. Same temp tstat, same rad..engine Set up the same..

I can take the cap off, fire it up and there's little bubbles, I'm hoping its not a head gasket.. they were brand new and I made sure both the block and heads were clean clean clean! And straight. Not burning anything out the pipes either..
No cats, just straight true duals, and its not eating through coolant either.

 

I have the exact same problem, and even the same engine set up. Mine gets hot pretty quick and stays right at 220ish. Yesterday was hotter and i noticed it was going up higher, closer to 230-240 by the time i got home. I popped the hood a lil while later and noticed coolant running down the top of the overflow bottle. I'm thinking I have some blockage in the radiator (it was used). I've got about 150 miles on it since I built it and have had this problem constantly. At first I thought maybe it was due to tight tolerances on the build, but now I'm leaning more toward the radiator. Has yours ever been flushed out?

 

wow, lol what are the odds. L98 cast heads rebuilt, stock valves and such. Frerra .35 head gaskets, 4.030 holes.

Its never been officially flushed, no. Everything was working great when I had the 305 in, the only time my temp got over 200 is on a really hot day, or if I was holding 5000+ rpm (mud car, getting through a 3 ft deep bog haha)

The block came out of a 80s truck, I drove it 40 miles home and that motor held 200, there was some crud in the coolant passages in the heads, but I believe I flushed most of that out.
Obviously new coolant..minus a little sweet tea that was in the rad (ran out of coolant in the truck, All I had was a gallon of Arizona tea hahah).
I can't turn on my heater, seeing as I don't have one, so I dunno if there's a bubble in the heater lines?

Tried burping the system last night, cap off, let her get up to 220.. there was a bunch of little bubbles that kept appearing for 20 mins, always the same amount, yet I'm not eating coolant. Levels are staying the same. No oil in coolant or coolant in my oil..
Has the right water pump, used the one that was already on the block, just switched from a vbelt to serpentine pulley.

Maybe I should put my old tsat back in?? Because parts store jockeys NEVER give the wrong part, hah.

 

The water pumps from V-belt and serp are different. If you just swapped the pulley, you have the wrong pump. You need a reverse rotation water pump for serp, you're spinning it backwards right now.

 

Its the same water pump that was on the block, still a v-belt pump, I just swapped the pulleys from my 305 but kept the pump that was already on it.

The only v-belt alternator I had was a little janky, my serpentine one was brand new, so just put that alt on, took the v-belt pulley off the water pump and put on a serpentine pulley. How would that make it spin the wrong way?

 

where are you pulling the temp from rear pass side or front driver side of the head..? and what I did was hooked a mechanical temp up to my water neck and just double checked my stock gauge. that will help you out to see where you are

 

maybe I missed it but are you only using the factory gauge? Mine reads about 220 when the aftermarket AND IR temp gun show 180

 

I was referring to the 1 serp belt that runs all pulleys. Yours is an 86, so you had a couple of shorter serp belts, right? Your water pump pulley has the ribs on it, not smooth right? I was thinking of the typical serp belt set up where the water pump pulley is smooth, because it runs off the backside of the belt.
The IR gun is also a good idea, to verify you're actually that hot. In my case, I am actually that hot.

 

I'm running it off of the sensor on the driver front head, I have an aftermarket gauge I can test with.
Dang, they're really that off? It read 190 on my 305, strange. I'll have to check with a ir gun or a diff gauge.
Today it was bouncing, strangely.

As in, highway, it was around 210, slowed down and it cooled to about 200, accelerated from the light and it rose back to 220.. sweet, air dam issue. Stopped at next light, stayed at 220, then dropped down to 200 once I was going. All city driving, to 50mph. Odd..

And yes I'm using a ribbed serp setup from an 86 t/a. Its running just my alt, water pump and crank, no smog er ac er whatnot.

One serp belt running around alt, crank and water pump, and a v belt on my crank and p/s pump

 

Safe to say, my ir gun is waaaay off. That, or I have a miracle motor.
Was showing 240 for cyl 1-5, 190 for 7, 270 for 2, 185 for 4 and 6, and 489 for 8. Exhaust pipe (headers, true dual straight pipes) showed as 87, yet its hot enough to evaporate water on contact. So either my motor runs on miracles.. or its junk.

 

Hooked up an aux gauge to the same sensor, read a solid 180. Hooked up the factory gauge to the sensor in my tstat housing at the same time, it was reading 220-260.

Thanks all for the help!

 

Wire up both fans so they run all the time. Shimming that center dam down a 1/2'' works good too.

 

I don't have 2 fans. Only came with a single, and I couldn't lower my dam, lol its a mud car, I need clearance.

The issue was my gauge. It was way off. Problem solved!