InlineDave87
Famous Member
Wouldnt suprise me. People in my are are cheap and willing to do almost anything to make a buck.
Mpg tanked again
- Thread starter InlineDave87
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That's a big economy drop. Be sure the SPOUT wire hasn't come unplugged. ??
Also, keep in mind that whenever you constantly watch your mileage you will notice almost any discrepancy. And it's usually with disappointment. Let's remember the rare occasions we got remarkably exceptional mileage. We didn't try to find or fix anything wrong then though. But maybe something was acting up as a precursor to the now glaring disappointment. Try to reflect on that and what could have made such a pleasing increase, and you may find it correlates.
Better milage is expected in the summer and in the coldest winter months, it will deteriorate noticeably.
Better milage is expected in the summer and in the coldest winter months, it will deteriorate noticeably.
InlineDave87
Famous Member
Im in south texas tho, we dont have winter.
Well when you first posted the bad mileage you were having a deep cold snap. And the wind down there doesn't play either when those fronts come thru. But this latest check with more normal weather is concerning. when the '90 was EFI I believe it would have gotten 13 running WOT, since it got just short of twice that normally on the highway.
A 5 mpg drop=38%. Need to look around and see what's up. Does it feel weak/sluggish? Spout wire? Clogged cat? Low tire pressure? . . I dun'no.
Typically it's not enough to call winter, by comparison. I'm in Houston where we never know what the heel it will be like tomorrow.
Did you happen to do a battery reset since replacing the thermostat? It's by no means necessary, just an ask
InlineDave87
Famous Member
Ive done some battery swaps since i replaced the thermostat. So i finally replaced my thermo gun and started taking temps. Yesterday morning i was driving on the highway and around town ambient temp was low 60s. My temp would go up with acceleration, and go down if i was cruising on the highway or decelerating. The first time i checked the temps my cylinder head was at 180 and my thermostat housing was 140. It did the same thing in afternoon when the temps got up the upper 80s. Checked the temps at home again and this time it got to 195 and the thermostat opened up. But again the temp would raise while accelerating and go down if i was cruising or decelerating. It only got up to temp when i got to my house and was letting it idle as i checked the cylinder head, the thermostat housing, and the radiator. I still think my radiator is too big ie, its the 2 row heavy duty radiator and not the standard 1 row. So the question becomes, do i replace the radiator, or just block some of it off cause the summer time does get hot (110+) and it could use the help. Im leaning toward KISS.
It does not sound like the replacement thermostat is acting as it should, in that it may be opening partially at a low temp and then fully opening when a high enough temp is reached. Another thought is during install the thermostat slipped out of place by a small margin, I always found them frustrating because of the vertical position; having to lean over and get two hard-to-manage bolts in far enough to keep it in place. Typically they show some external leaking but not always if a thick enough gasket was used, or enough sealant.
Has your power changed any?
Has your power changed any?
InlineDave87
Famous Member
Power seems normal. Its about as good as its going to get being a stock motor. Ive been tempted to take care of some parasitic losses and open up the exhaust but dont know if its going to be worth my time. I want to upgrade the rockers, get rid of the air pump, go with an electric fan. And im even thinking of insulating the fuel rail as when i checked it yesterday too the rail was up at 170-180. I know we can get more umpth from just cooling off the fuel, which is making me think this is why they are prone to knocking at higher temps and the need for the egr. Wish i had the time to experiment but this is my work truck too.
Does the truck take any longer to warm up? Another way of checking for an open thermostat is when you crank it up cold, go hold onto the upper radiator hose. If it gradually grows warmer then the thermostat is already open. The hose should stay close to your starting temp and then abruptly get hot when the thermostat opens if it is working correctly.
Since blocking off the radiator is a basically free (or very low cost) modification that can be easily reserved (by pulling out the coroplast), it seems as if that would be the most cost effective solution, even as if just a first step. BTW -- that is a common tactic on the Ecomodders forum.
InlineDave87
Famous Member
I think its partially stuck open. The top hose was pressurized even when the temp read 180 on the head and 140 on the housing. I have a new thermostat, housing and radiator hose on order. Im wondering if this was why the shroud was left off when i first got the truck. I had a spare one and added it.
InlineDave87
Famous Member
I remembered i had this thin piece of wood. I took quick measurements of the radiator and got 27” wide x 21” tall. I cut a 7” wide piece x 21” tall, found a good little pocket for it to slip into. If it proves to be a problem i can remove it. It clears the fan and the shourd keeps it in place. Im gonna see how it does with 25%ish blockage roughly down the middle. This is just for testing/experement purposes. I have a motorcraft thermostat coming in on friday and will swap it out then. I got to take my long road trip tomorrow so well see if this helps bring the temps back to operating range. I also verified my tire pressures were good. I have to go pick up my daughter from school right now so i get to do a little test run. In case it starts over heating i can always pull over and cut the zip ties remove the board and retie the shroud back down. Ill keep you guys posted.
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InlineDave87
Famous Member
Made it to my daughters school. So initially the truck warmed up real quick. It got between the N and O then you can see the thermostat kick in and the temp dropped almost all the way to cold, right where the range starts. And as i continued driving the temp slowly came back up which to me tells me the radiator is too big or the thermostat is flowing too much. I let the truck idle for 5 minutes just to make sure she didnt overheat and it seemed fine. While my blockage is roughly 25%, my guess since the radiator is double the capacity, its really more like 12%. Im thinking of cutting another piece 9” wide which would make 33% coverage and i think effective would be closer to 17%. Does that make sense or am I pulling out of thin air? Im having this issue and i probably got like 300 lbs of tools and stuff in the bed of my truck. 
Dave- There's a huge radiator in the '90 f150, with 3 or 4 rows. got it from Summit. It ran cold forever with a new t'stat installed 10 years ago when the partial rebuild wad done and that rad was installed. I always said too much radiator. I've already mentioned that I recently installed a FlowKooler Robert Shaw Tstat. Engine is to t'stat temp in 5 minutes, one drop-serge when it first opens, then holds temp from then on. first time there's been decent heat since I've had the thing! You need another t'stat.Made it to my daughters school. So initially the truck warmed up real quick. It got between the N and O then you can see the thermostat kick in and the temp dropped almost all the way to cold, right where the range starts. And as i continued driving the temp slowly came back up which to me tells me the radiator is too big or the thermostat is flowing too much. I let the truck idle for 5 minutes just to make sure she didnt overheat and it seemed fine. While my blockage is roughly 25%, my guess since the radiator is double the capacity, its really more like 12%. Im thinking of cutting another piece 9” wide which would make 33% coverage and i think effective would be closer to 17%. Does that make sense or am I pulling out of thin air? Im having this issue and i probably got like 300 lbs of tools and stuff in the bed of my truck.
As far as a board to block the radiator- been doing that for 10 years, till this new t'stat. Mine slides nicely infront of the rad/AC condenser. That way no chance of coming loose and getting into the fan. Mine is 10" wide, same height as rad.
InlineDave87
Famous Member
Yea thats what mine did, and it looks like the board i cut was sufficient. After some more driving around it got up to temp slowly and stayed there. I got my long road trip in the morning so ill see how she does from there. When the temp finally stabilized and got to operating range, the power felt like it came back and wasnt sluggish like i have been having issues with.
PSIG
Well-known member
You can't have too much radiator to maintain minimum temperature. Consider a boat, with an endless supply of millions of gallons of cold lake water. It has to come up to temperature and hold it. That's the job of the thermostat, and unless it's not functioning properly, will do that job.
InlineDave87
Famous Member
Ok but on a boat it has a huge flow restriction that allows it to get up to temperature. That flow restriction makes the water move slower allowing the engine to build up heat. Thats why the water coming out is barely bigger than a pin hole and not like a garden hose. In the case of my truck or any truck, the radiator not only cools the coolant but acts as the main reservoir too. Having extra capacity allows the coolant to sit and cool more while in the radiator before it can cycle thru. All i did was create a wind dam so that the cooling effect is less allowing the engine to warm up normally. Im in south texas and we normally see 110+ weather in the summer so getting up to temp wont be an issue then. But right now that we are barely seeing 80, the radiator is performing “too good”. It might end up being the case that im going to have to save this board for the winter months. Diesel truckers do this too via a grill screen up north so the engine can run right and they can have heat in the cab. Which that was my problem too on the first road trip out that my temp barely got into the range and the temps outside were upper 20s.
Also work got pushed back to tomorrow, so ill figure out if this helps my fuel economy.
Note:
“The information written below was edited in some areas so a better understanding may be obtained when reading.”
I respectfully disagree,
One of the problems with the 300 six is the front cylinder gets blasted by cold water in very cold days. “This is what we try to avoid”.
Having a very large radiator in a vehicle while driving in -20 degrees below F. and colder can be hard on an engine if proper steps are not taken to limit the amount of extreme cold air blast on the radiator.
When temperature drops to extreme sub zero digits, the radiators in all my family’s vehicles up north are closed up some to help reduce cold coolant entering the engine block.
The thermostat allows hot coolant to pass when needed. And where does the expelled coolant go? The radiator.
Too large of a radiator having its core blasted by extreme artic weather cools the coolant fast and low enough that the engine can be harmed by the initial shock of the cool coolant leaving the radiator and returning to the engine block. This is reduced by running the OEM radiator that was sized properly by the manufacturer. Or partially blocking the radiator core. Warmer coolant entering the engine block is a good thing. It lessens the initial shock to the engine block.
Why do large 18 wheeler trucks have dampers installed on the grill? Or temporary curtains? To prevent what I just written above.
About cooling systems in boats, There is a difference in fresh water and raw water cooling. Raw water cooling can be very hard on inboard and I/O engines. Fresh water cooling is better for most boats. It’s much easier to set one up to regulate coolant temperature going back to the block. I’m not going to get into it. It’s too long too discuss it here. The same principle applies with engine cooling systems in boats. They are discussed in other forums.
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A good thermostat can keep temp stable at the outlet where it is judging regardless of incoming coolant temp-true. However excessive cooling of incoming coolant causes a bigger temperature differential across the engine, and frequently cause an automotive t'stat to surge. They all surge on first open, as the rad is ambient temp. The recommended temperature differential water-out to water-in for big diesels is 10*F- that's it. A radiator that "barely" cools enough to maintain balanced t'stat temp is the best for extended engine life. (This is not an opinion).
It's not a balanced comparison to bring small gasoline marine engines into the discussion, because they see an extended high load at stable rpm, something an automotive engine does not see most of the time.
Large diesels have a thermostat (or a pair of them) that act as a full-flow bypass. When closed, they don't choke off and stagnate the coolant in the engine. There is full flow thru the block and head at all times. As the t'stats open, it increases the proportion of coolant allowed through the radiator while reducing what is being recirculated. This is far superior to automotive, as there is no surge of cold rad water all at once. This design eliminates the "too big" radiator issue, and keeps incoming coolant temps very stable.
Keel-cooler marine applications (this is a closed coolant system, cooled by a series of long tubes on the outer hull of the vessel which radiates coolant heat into the seawater). These systems have a merge junction where the outgoing and incoming coolant meet, separated by a fine-tunable valve. The purpose of the bypass valve is to regulate the incoming cooled coolant so that it is not too cold, preferable close to 10* cooler than the t'stat temp, or as warm as possible to still maintain stable operating temperature.
It's not a balanced comparison to bring small gasoline marine engines into the discussion, because they see an extended high load at stable rpm, something an automotive engine does not see most of the time.
Large diesels have a thermostat (or a pair of them) that act as a full-flow bypass. When closed, they don't choke off and stagnate the coolant in the engine. There is full flow thru the block and head at all times. As the t'stats open, it increases the proportion of coolant allowed through the radiator while reducing what is being recirculated. This is far superior to automotive, as there is no surge of cold rad water all at once. This design eliminates the "too big" radiator issue, and keeps incoming coolant temps very stable.
Keel-cooler marine applications (this is a closed coolant system, cooled by a series of long tubes on the outer hull of the vessel which radiates coolant heat into the seawater). These systems have a merge junction where the outgoing and incoming coolant meet, separated by a fine-tunable valve. The purpose of the bypass valve is to regulate the incoming cooled coolant so that it is not too cold, preferable close to 10* cooler than the t'stat temp, or as warm as possible to still maintain stable operating temperature.
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