I have a quick question for anybody with a 5.0

What degree rating should the thermostat be? I put in a 180 right after I did my engine swap and my gas mileage has steadily gone downhill, to around 12-13. I have a 5 speed, and 3.08 gears, ao I should be getting better mileage than this. Should I bump it back up to a 195, I also have been running Red Line Water Wetter in my radiator. Which I am going to be having flushed. I'm probably not going to be adding the water wetter back to my cooling system afterwards because I really didn't notice that much of a difference.

Thanks guys. My main concern is for the fuel mileage.



1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
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1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.

Can see both below.

[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]

 

Stock is a 195 degree stat. I know it seems kinda high, but that's the way they made it.

1989 F-150 : 5.0, shorty headers, Flowmaster cat-back, K&N filtercharger intake, March pulleys, "Multi-brand" performance ignition, soon to be Mass-Air...doesn't know she's not a Mustang

 

Thanks man, I'm going to definitely look into it. That could be the majorty of my problem, with the truck not wanting to run right, and hesitating. I cleaned the throttle body a month ago, and it still doesn't want to run worth anything.


1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.

Can see both below.

[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]

 

I have always used 195 degree thermostats. I recommend it too. I have never gotten any of my trucks hot ever. Even idling in over 100degree weather it never get's above the "o".

 

Thanks, I'll look into replacing it very soon. My temp guage almost never gets to above N on the guage. Maybe this has been my problem all along?


1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.

Can see both below.

[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]

 

Mine is usually right on the left line that separates cold from normal. And I don't think any of the previous owners ever messed with the thermostat.

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1988 F-150, 5.0L 302ci, 5spd, SuperCab. Shorty headers, K&N filter, Accell 300 8.8mm race wires, Accell supercoil, Accell rotor+cap, Bosch +4 Platinum plugs, RanchHand bumper, MSD 6a ignition just ordered. Next: dual exhaust.

 

[font size="1" color="#FF0000"]LAST EDITED ON 25-Feb-01 AT 10:18 PM (EST)[/font][p]Hotrod, It does sound like the thermostat when you mention hesitation and not running properly. All of my Fords ran between the "N" and the "O" leaning more on the "N". All had original spec thermostats. I had an 86' F-150 that was a little out of wack because of cooler running. Thermostat acted up and needed to be replaced. Jake.

Jakegypsum // Ford fleet, soup to nuts.

 

Hotrod_88, alot of times the thermostat can play head games with the computer so I would reccomend staying with the stock degree then the computer knows when to take it off high idle and when to lean it out and so forth. John

 

Thanks, I intend to pick up a new thermo tomorrow! I'm going to get one of the really good balanced thermostats, I think alot of racers use them, and they are supposed to be the best at opening on time and what not. Maybe worth the few extra bucks, I don't know. But I have got to do something about this gas mileage, after all this is a 5 speed with 3.08's! I should be getting much better than what I'm getting now.

I also have an exhaust leak to fix tomorrow, one of my headers keeps working it's way loose on the head in a couple of spots. I used the "best" allen head header bolts! Yeah right, they won't stay tight, and where they do stay tight is where I put in the original header bolts that came with the headers. Thankfully I still have the good bolts that they came with, and they will be going on tomorrow as well.

1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.

Can see both below.

[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]

 

John, it didn't click until you said something, but mine has been idling high, really high (1500 rpm) and will constantly idle rough, even the new plugs I installed about 4 months ago never helped. I probably will have to do a tuneup on it next month anyway, so, new plugs and a new O2 sensor will be in order then.

Thanks guys, you have convinced me to swap that temperature controller out.



1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.

Can see both below.

[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]

 

Hotrod, What type gaskets are you using? I have had problems in the past using thick type gaskets like Felpro. I myself had better luck with the thinner tin type gaskets. Ford stock gaskets. I am not sure if you can use them with the type of headers that you have though. Just a thought. Jake.

Jakegypsum // Ford fleet, soup to nuts.

 

I'm not sure who made these, I think they are Mr. Gasket, some of their better ones though. I bought them at one of the local places that deals in speed parts. I know it's not the gaskets, I have to re-tighten these goofy bolts every time I hear it start leaking. So this time they come out, and the good ones go back in. Even though they are a pain to get in there and tighten, they are going back in.



1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.

Can see both below.

[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]

 

Yup, those bolts can be tough. Tough on the fingers too. My problem with thicker gaskets was the spongyness of them. It almost seemed like they would literally push the bolts out between the spongy pressure and the vibration of the engine. I switched to stock type gaskets and eliminated the problem. Good luck.

Jakegypsum // Ford fleet, soup to nuts.

 

Mine aren't spongy, they are metallic. But they are really good gaskets. The only side that seems to work it's way loose constantly is the passenger's side. It's a real pain at times.

1988 F-150, SWB, 5.0 EFI (formerly 4.9 EFI), M5OD 5 speed, 3.08 gears, Summit shorty truck headers, Custom built Flowmaster exhaust system. Force 4 LP6000 lightbar, Federal signal PA-300 100 watt siren, Icom IC-V100 50 watt mobile radio.
=======================================
1965 F-100 (just purchased 1/18/01), SWB, 390, C-6 auto. Dual exhaust, Not much else to do to it.

Can see both below.

[link:www.geocities.com/hotrodford_88/|Hotrodford_88's Webpage]

 

HRF_88:

I think you and I have the same header set-up. I've got those Summit flowtech headers with the Mr. Garsket copper gaskets (?). I know those bolts are hard to get to, and I was gonna buy a set of allen-keyed ones from Summit, and they have a locking set. They're, like, 35 bucks or something.


1989 F-150 : 5.0, shorty headers, Flowmaster cat-back, K&N filtercharger intake, March pulleys, "Multi-brand" performance ignition, soon to be Mass-Air...doesn't know she's not a Mustang