running hot

[savage]

I'm curious, on my 74 rebuild 302, I don't run a heater, so I've just looped the heater hose from the water pump to the manifold. Can doing this cause my engine to run hotter? If so, should I take the hose off and put a plug in the intake and cape the water pump? It runs around 183 to 195, in 70 plus weather, and sometimes will hit 200 in stop and go traffic.

 

[DirtDonk]

Well first let's get this out of the way. That's not hot. It's not even at the high-warm level yet.
Your engine is happiest at those numbers anyway. But if you've got a 160 thermostat I can understand how you'd be concerned. But you should be more concerned that it might run at 160 which is too cold for a normal engine and is only an old-timers trick to keep detonation down while turning up the ignition timing for racing.
Otherwise, street engines want to see 190 all day long.

What t-stat are you running? And why the concern? Does it go higher?

Paul

 

[DirtDonk]

What is your ignition timing set at by the way?
And do you have a PCV valve in the other cover?

 

[savage]

What is your ignition timing set at by the way?
And do you have a PCV valve in the other cover?

It's 180 thermostat , I'm not positive on timing, I think it's 10 ,but I'll pull the timing light out and see. The other valve cover has a PVC valve. The highest I've seen it was 210 in stop and go traffic, with temps in the high 80's, but that was a year ago and I've put vents in the hood and sealed the front top of the radiator, and its actually lowered the temps by 10 degrees. Would more timing help. I guess I should not compare it to my dodge Cummins, which runs cool all day.

 

[DirtDonk]

How cool does the Cummins run? And what year is it and has it been modified.
But no, you should not necessarily compare them, but they could be closer than you think.

For your 210, just so you know the "normal" operating temp of a GM LS motor is 215.
Just sayin'... But again, it's not apples to apples, even though these are two gas engines being compared.
The standard Windsor thermostat for many years was the 192 or a 195, so even at 200 you're only 5 to 8 degrees above the rating. Well within the design criteria, and nowhere near running hot.

The reason I mentioned ignition timing is that if it's too retarded it's very easy to bring temps up. When you get the timing light out, don't just check the base timing at idle, check it through the rpm range while looking for consistency and continued advance until it's fully in. And note at what rpm it maxes out at.
Lots of people have failing advance mechanisms (sticky, bent, broken, whatever) or have disconnected the vacuum advance for whatever reason and find that the engine runs hotter for it.

Paul

 

[Timmy390]

T-stat rated temp is when it "starts" to open. It's not fully open till 12-15 degrees above that.

With stock 1996 351W 195 stat, I run 210 on mechanical gauge.

Tim

 

[savage]

How cool does the Cummins run? And what year is it and has it been modified.
But no, you should not necessarily compare them, but they could be closer than you think.

For your 210, just so you know the "normal" operating temp of a GM LS motor is 215.
Just sayin'... But again, it's not apples to apples, even though these are two gas engines being compared.
The standard Windsor thermostat for many years was the 192 or a 195, so even at 200 you're only 5 to 8 degrees above the rating. Well within the design criteria, and nowhere near running hot.

The reason I mentioned ignition timing is that if it's too retarded it's very easy to bring temps up. When you get the timing light out, don't just check the base timing at idle, check it through the rpm range while looking for consistency and continued advance until it's fully in. And note at what rpm it maxes out at.
Lots of people have failing advance mechanisms (sticky, bent, broken, whatever) or have disconnected the vacuum advance for whatever reason and find that the engine runs hotter for it.

Paul

My Dodge is a 1997 2500 4x4 5.9 Cummins. It is modified with a Banks Power Package which can produce up to 30 lbs of boost, which I only have push it as high as 20lbs of boost and a built 47RE transmission. It runs from 160 to 190 all day. The 5.9 thermostat is known for a lot of fluctuation which is normal I was told. So Paul you don't think the way I've by passed the heater core, can make it run a little hotter? I'll get back to you on what the timing was.
Thanks Dave

 

[savage]

T-stat rated temp is when it "starts" to open. It's not fully open till 12-15 degrees above that.

With stock 1996 351W 195 stat, I run 210 on mechanical gauge.

Tim

The readings are, all so from a mechanical gauge on my bronco. So from what your saying, with a 180 thermostat, it will be fully open at 192 or 195. So then my engine is running at the wright temps.

 

[Timmy390]

The readings are, all so from a mechanical gauge on my bronco. So from what your saying, with a 180 thermostat, it will be fully open at 192 or 195. So then my engine is running at the wright temps.

Correct......It's running within "normal" range IMO.

Could it be cooler? Sure could. The creep in stop and go traffic sounds like an air flow issue.

How much is it bored over? Compression ratio? Those two things can cause an increase in temps over stock.

I would verify timing, fan clutch, fan blades, fan distance to radiator, radiator blockage etc. What is the idle set at? Maybe raise it to get more air at the stop lights. You have a fan shroud which is good. Adding the Explorer front dress is the perfect way to keep things on the cool side. It moves HUGE air and I wasn't such a stubborn SOB I would have added one when I installed my W rather than using the van front dress I already had.

I run an electric fan controlled by my ECM.

Tim

 

[DirtDonk]

...So Paul you don't think the way I've by passed the heater core, can make it run a little hotter?

I forgot to touch on that. Yes, it can skew the readings, but I don't think I've ever heard of anyone saying that it caused the engine to run overly hot.
It does have the potential to change the coolant flow pattern in that area that just happens to be near the coolant temp sensor, and it's been reported that on some engines it can mess with the flow enough to actually change temps.
But again, I've never seen that. But I have seen literally hundreds of vehicles over the years with a loop of heater hose bypassing the core.

Can't say that I know whether or not most of those had any experiences with temperature changes after bypassing, but a few people that I know personally (including me for a short time with a leaky heater core) never had a problem.

Doesn't mean it couldn't happen. Just that it has not in my experience.
You could test yours by capping the ports off instead of looping them together. That way if there is any flow change from bypassing you'll see it on your gauge.

Paul

 

[savage]

Correct......It's running within "normal" range IMO.

Could it be cooler? Sure could. The creep in stop and go traffic sounds like an air flow issue.

How much is it bored over? Compression ratio? Those two things can cause an increase in temps over stock.

I would verify timing, fan clutch, fan blades, fan distance to radiator, radiator blockage etc. What is the idle set at? Maybe raise it to get more air at the stop lights. You have a fan shroud which is good. Adding the Explorer front dress is the perfect way to keep things on the cool side. It moves HUGE air and I wasn't such a stubborn SOB I would have added one when I installed my W rather than using the van front dress I already had.

I run an electric fan controlled by my ECM.

Tim

It is bored .60 over which I know is to the limit, I told him I could find another block, engine builder was not to worried they specialize in fords, I know the Mexican blocks are thicker in certain area's. Not sure what the Compression ratio is it's was build a couple of years ago. when it comes to fan(WH 7 BLADE) ,shroud(stock), radiator( Toms aluminum stock replacement), I've put vents in hood which helped and put a aluminum air dam to top of radiator. When it comes to the idle, it's set around 750 rpm in gear with a C-4 tranny. I'm thinking the radiator is not large enough ,and was looking at WH 4 core W/TRIPLEFLOW radiator. This weekend I'll look at the timing.

 

[Timmy390]

.060 over could be part of the issue. I don't like and wouldn't personally go that far over. Many do and have no issues but then there are those that do. I don't take those kinds of chances.

Check for air flow at idle by seeing if a dollar bill will stick to the radiator. The fan should be pulling enough air to hold the $1 on the radiator......

Tim