Thread: 348 Running warm

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Originally Posted by 53 Chevy5

I am just about afraid to ask this because of embarrassment, but is that necessary? I found a fitting and some hose this morning and I am going to put one on right away. I need to drive it about 100 miles today for some exhaust and run some errands.

If you get a chance to install the bypass before your trip today, please provide an update after you return. I'm hoping that you'll be pleasantly surprised. And 36 sedan provided a great answer as to why the bypass is needed (Chevy went to the trouble and expense for a reason).

Good luck!!

Originally Posted by 53 Chevy5

I found a fitting and some hose this morning and I am going to put one on right away.

It's hard to make that tight bend with a piece of straight hose without kinking. Using a pre-bent 90 trimmed to length makes it an easier job....

I looped a hose from the pump to the heater hose port for the time being and it was the same song and dance. Drove for about 6 miles and watching the gauge go up and down nice and then boom , decided to go to 205 and stay there, it was only 75 outside this morning. I'll hook the the bypass where its supposed to go and try it again, but I think it is a pump problem. On a side not oh my gosh this thing sucks gas. I have a 22 gal tank and I thing I can actually watch the gauge drop as I drive.

Heck with it, I was at the muffler guy today and he seen the 348 and the first thing he said is " those 348s are cool but they suck fuel and love to overheat " I checked the mileage on my short trip and it was getting 5 mpg. Best case I can get it up to 10. I got a 5.3 coming with all accessories, wiring harness ready to go, fuel lines exhaust sections from manifolds, the whole drop in ball of wax for $1100. I want to drive the wheels off this thing.

I agree, not much fun to this hobbie if you cant drive it, but on another note they didnt make that series of engines (348 & 409) I am sure for 5 years or so I wouldnt think if they all overheated, I know your patience is probably thin but somethings missing or wrong and I have this hunch that somebody could by a cool old motor for a pretty good deal if they where willing to figure out the problem, sure would look good in a streetrod! But do whatever it takes to enjoy the car your way and have something your comfortable with. Matt

Originally Posted by Matthyj

I agree, not much fun to this hobbie if you cant drive it, but on another note they didnt make that series of engines (348 & 409) I am sure for 5 years or so I wouldnt think if they all overheated, I know your patience is probably thin but somethings missing or wrong and I have this hunch that somebody could by a cool old motor for a pretty good deal if they where willing to figure out the problem, sure would look good in a streetrod! But do whatever it takes to enjoy the car your way and have something your comfortable with. Matt

I'm not overly bitter about it, as I got older in the back of my mind I knew I was going to swap this motor out for a 5.3 some day just didn't think it would be this quick. I'm a ag mechanic all day and I don't enjoy tinkering with nuts and bolts at night like I used to. I've been hiring people to fix my stuff while I get paid to fix others The mileage thing is what really did it for me. I'm going to keep messing around in the mean time to see if I can get it to cool better while I wait for my guy to get the 5.3 ready. Not sure if its going to happen without V belts or a proper reverse pump, but maybe I'll run into something stupid that I did again I seen a 53 chevy wagon on craigslist that I am constantly talking myself out of buying and putting the 348 in , kinda like a rat rod thing. I need another project like a hole in the head.

Let me know when you're tired of that pesky Camaro thing..........................

Originally Posted by 40FordDeluxe

Let me know when you're tired of that pesky Camaro thing..........................

You know how to do it, ask when I'm sick of everything How about a 77 T/A instead, Silver in color red cloth interior, t tops, 4 speed. Hmm Ehhh, here fishy fishy

No thanks. I have a bad spot for 70-73 Camaros. I'm half tempted to trade my challenger for one.

Originally Posted by 40FordDeluxe

No thanks. I have a bad spot for 70-73 Camaros. I'm half tempted to trade my challenger for one.

I know the feeling, I would sell the T/A tomorrow if my kids would let me, but I just can't break ties with the Camaro. I think I'll end up starting on that one next year, doing the stuff I can to for free to re coup the wallet from this 53. Then I think I'm going to start with the Interior and go with a Ls swap on that one.

I put about another 50 miles on the 348 in 90 deg weather. I could be wrong but I think this is what the deal is. I think I have a water capacity problem.The motor holds like 4 gal of water or something like that, and the radiator doesn't hold enough cool water to cool down all the hot when the time comes. Like trying to cool down a gallon of 200 deg water one cup at a time. That's if the water had time to cool in the rad b/f the thermostat doesn't open and creates a loop of hot water. The motor will cool just fine for about 6 miles or so and if the thermostat stays open during one cycle, it's screwed. If I drive 55 and watch the temp and as soon as it hits 200, I slow down to about 45 and it will cool it down. I took a heater hose off and the pump seems to be pumping like crazy and the air getting pulled through the radiator with the fan is freaking hot the whole time its trying to cool until it does cool down, then you can feel the temp difference during the cycle. That tells me its pumping good but the I just have a lot of water to cool. I pulled the shroud off and that helped some down the road and hurt some in town. Like I said, I think that's what is going on, not 100% positive but that's how I read it. I would love to try a made reverse flow pump or change the impeller back to standard flow and v belt it but I think tuning the page to a more driver friendly motor is better time and money spent. I am hoping to sell this motor and trans together and cover the cost of the 5.3 swap, and maybe put a little in my pocket

btw., the purpose of the bypass is to allow a small amount of water to flow at all times.
Without it - the thermostat will not get any of the hot water in time, the really hot water will be trapped in the motor and will boil before the thermostat opens.
You need to have some water flowing at all times so it can all work as a system, if the flow stops, the hottest water won't reach the thermostat .

I think you said you removed your thermostat, so this wouldn't be your problem.. just wanted to share info is all.