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2020 7.3 ford

Started by snowstorm, February 05, 2019, 08:24:43 AM

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square1

Quote from: snowstorm on February 10, 2019, 05:12:17 PM
Quote from: moodnacreek on February 10, 2019, 04:23:47 PM
Wasn't the 7.3 a gas engine to begin with?  I think it was based on the IH v8 that replaced the 304-392 for the epa rules. My '91 f350 pu has 200,000 and gets 20 mpg running lite. Only problem it's only 185 hp.
that would have been the 404    446 gas that ih came out with in the late 70's? also a 537. they replaced the older gas motors. i never heard the 7.3 came from that. they used to say way back that the 1160 cat was styled after a 534 ford. the 1160 later became a 3208
Because the 6.9, and later 7.3, shared many bolt on components with the 404-446 gasser to capitolize on an established replacement parts supply many believe it was a converted gasser..  Inside,  it's a diesel, having oil spray cooling on the piston skirts, etc... The bare 6.9 / 7.3 block weighs several hundred pounds more than the gassers.

moodnacreek

Square 1, thanks for that post.

mike_belben

The 7.3 idi was born from the 6.9idi block by overboring it due to low power complaints.  The original casting was sufficient for 6.9 but not 7.3 so thats where the cavitation issues come from, too little cylinder wall.  Over time and billions of cycles, the pressure waves in the coolant cavity lap the shores of the cylinder wall backsides and this water against metal action erodes from the water jacket until a pin hole breaks into the liner and leaks.  I suppose sleeving is an option but overboring early 7.3 is certainly risky business.  SCA coolant additives may as well have been invented for the 7.3 idi. Itsna plastic coating so that the erosion eats the coating instead of metal. Just dont let it run out. 

Another issue was the 6.9 had a loose valve seal that consumed a lot of oil and carboned up the back of the valves so they went much tighter on the 7.3 version but erred on the too tight side so valves were prone to starve of oil, wear the guide and stem, in extreme cases break the valve face off and drop it into the hole.  I think itsna wives tale that they wore the stems that thin.  It doesnt take much loss of guide lubricant to gall the stem into the guide, stick open a second, and bend the pushrod/smash the valve face off.  

Anyway these are the two potential disasters in the early navistar idi, [kinda like the cummins 53 block cracking or potentially owning a 6.2gm diesel  ;D ] the rest is just basic maintenancy stuff.  I think the 6.9 may have also had insufficiently sized head studs that were bumped up in the 7.3 but my memory is foggy on that and i could be wrong.

I hated the fuel system on my idi.  It was the hardest priming truck i ever had and i parted ways with it during one of the rare instances when the thing was running well.  
Praise The Lord

moodnacreek

Mike, the 7.3 idi  I mention has been with me since '92. The Roosa master style pump has been disappointing . Been through at least 7. Dumbest thing I did was buy cheap ones off E bay [diesel care]. Although the pumps won't last 100,000, if the pump is done right the engine runs well and gets good fuel mileage. I can change the fuel filter, start right up and drive away without a miss. Now don't get behind me if I got the trailer on !

mike_belben

I thought stanadyne made those fuel systems?   I dunno, i had the displeasure of owning that one for maybe a year and wrote them off.  No idi's or v8 diesels allowed in my life. 6BTs and DT466s and 13speeds i know are worth the overhaul.  Can i find a 6lug budd 22.5 to save my life?  No.  No i cannot.  
Praise The Lord

starmac

I had good luck with my 6.9 and 7.3.
the 83 and 4 6.9's had a weak spot around the freeze plugs, if the block heater was used much they would crack.
That issue was dealt with for the 85 ,6 and 7 models.
The 87 models were best as they had several of the improvements that the 7.3 had, Rocker arms, oil cooler and the glow plug system.

the head bolts were a size bigger on the 7.3 engines, so the heads will not interchange, but the improved rockers will, as will the oil cooler and glow plug system.

It seemed like every 7.3 that I ever was around that wound up with cavitation problems, did so at 120,000 miles or less, if they lasted longer, it was rare for them to go bad. I always thought they had some bad castings.

The smaller head bolts never caused me any problems on the 6.9's but would if you added a turbo and didn't limit your boost to around 12 pounds, arp studs cured that problem, but were kind of spendy. The 7.3's would handle 20 pounds with stock bolts.

I had good luck with them, and when they came out they just had to be better than the 6.2 chebby, which was no chore.
I do prefer the cummins though for several reasons, just preffered the ford pickups back then, new ones are about all the same.
Old LT40HD, old log truck, old MM forklift, and several huskies.

ohiowoodchuck

Quote from: starmac on February 12, 2019, 04:52:43 PM
I had good luck with my 6.9 and 7.3.
the 83 and 4 6.9's had a weak spot around the freeze plugs, if the block heater was used much they would crack.
That issue was dealt with for the 85 ,6 and 7 models.
The 87 models were best as they had several of the improvements that the 7.3 had, Rocker arms, oil cooler and the glow plug system.

the head bolts were a size bigger on the 7.3 engines, so the heads will not interchange, but the improved rockers will, as will the oil cooler and glow plug system.

It seemed like every 7.3 that I ever was around that wound up with cavitation problems, did so at 120,000 miles or less, if they lasted longer, it was rare for them to go bad. I always thought they had some bad castings.

The smaller head bolts never caused me any problems on the 6.9's but would if you added a turbo and didn't limit your boost to around 12 pounds, arp studs cured that problem, but were kind of spendy. The 7.3's would handle 20 pounds with stock bolts.

I had good luck with them, and when they came out they just had to be better than the 6.2 chebby, which was no chore.
I do prefer the cummins though for several reasons, just preffered the ford pickups back then, new ones are about all the same.
I lost a 2001 7.3 at 270k due to cavitation. It ate at the cylinder wall at the number 5 hole until it finally got so thin it cracked and filled the cylinder with antifreeze. When I started it, it busted the piston and bent the rod. I didnt know it happened when it it done it. I just noticed a loss of power and white smoke. Then my engine oil level started going up. If you left the radiator cap loose it would run like a top, tighten it down and it would run like crap  I put another engine in it. 
Education is the best defense against the media.

moodnacreek

Quote from: mike_belben on February 12, 2019, 02:17:22 PM
I thought stanadyne made those fuel systems?   I dunno, i had the displeasure of owning that one for maybe a year and wrote them off.  No idi's or v8 diesels allowed in my life. 6BTs and DT466s and 13speeds i know are worth the overhaul.  Can i find a 6lug budd 22.5 to save my life?  No.  No i cannot.  
Stanadyne bought out Roosa. I am not fond of V 8 diesels myself,rather have inline with mechanical inj. pump but I could never afford what I really want and won't finance a pleasure vehicle.

mike_belben

Well, that last part i am familiar with.
Praise The Lord

starmac

I am fond of the one payment plan myself. I have financed plenty of big trucks, but sitting here thinking, I think the last pickup I financed was a new 79 F 250. 6911.00 tags, title and plates, wouldn't even make a down payment these days.
Old LT40HD, old log truck, old MM forklift, and several huskies.

mike_belben

We can thank the federal reserve's " two percentent inflation TARGET" and other unsound monetary policies for that one.  

The utility of a truck is unchanged from then to now and the need for a truck is probably even less than it was then for most regions of the country.  The money value has changed, not the big mac or BTUs in gallon of fuel. 
Praise The Lord

starmac

Mike that is one cause that had an impact on it, but there were several others, some by the government had major impacts on what was built.

One major factor was people changed, their wants changed. I watched it in the 70's when pickup prices doubled, folks that basically had little or no use for a pickup started buying them, soon and I mean within just a year or two it went to hey I have a pickup in the driveway, I might as well have a 4 wheel drive one, in case I ever get close to a curb or something, then they wanted more luxury, so they could do away with the family car.  I can remember when the 4x4 craze hit, it was not farmers, ranchers, construction companies, oilfield companies, etc buying them, or even country folks, but it seemed like in the span of a year or three every other driveway in the cities had a 4x4 sitting in it. Then they started getting bigger, more power, and every year more luxurious, the basic utility work pickup has been phased out pretty much completely.

This is not just with pickups, the same thing has happened to everything from houses to lawnmowers, and bicycles and atv's to semi trucks and farm tractors.

Can you imagine if we had to, starting tomorrow, go back to a 2 wheel drive hot water six with a 3 on the tree pickup, with the only option being a heater.
It would be a major learning curve and many folks would not even be able to get it out of the driveway, till they learned and replaced a clutch or two. lol
Old LT40HD, old log truck, old MM forklift, and several huskies.

barbender

I know I don't need everything they put in a new truck. Power doors and locks, a/c I like but most of the luxury items are just things that get broke or ratted out right away on a working truck. Shoots, I can't even seem to keep those luxury fenders on my dually!😁
Too many irons in the fire

starmac

In 08 my son was in dire need of a newer dependable pickup, so we went looking for a used one. It seemed like everything we found that was what he wanted was in the 19 to 20 thousand range with over 100,000 miles.
I told him let's just get you a new one, so started shopping with several dealers, 2 or 3 days later I had several prices for the same pickup and the local dealer said he would match it, come on down. when we were there a few days before he tried hard to get me to trade my old, dually in, that we were driving, told him he could forget that idea, while we were test driving pickups, he kept turning around and talking to me in the back seat explaining how nice this option or that was, until I finally told him he had better be talking to my son if he wanted to make a sell at all.

Well it was 65 miles down to the dealer, so I told him to have the paper work ready when we got there, we got there and he said no way could he match that price, and the other dealer couldn't sell it for that either and wanted to see the spec sheet. I told him he had exactly 30 minutes to match the deal and my signature on the paper, it was 100 miles the other direction to the other dealer and we were driving a pickup home today. After studying it for a while, he said it was not the same specs. I argued the point and he pointed out that the one at the other dealer did not have an easy lift tailgate. I told him that I figured if that 18 year old 200 pound boy couldn't lift a tailgate, he didn't need to be driving period.
We left and he was on the phone with my son before we got 2 blocks away wanting us to come back, my son told him he doubted if he could sell me one if he knocked a thousand or two off, and we were now in a hurry to get to the other dealer.
Old LT40HD, old log truck, old MM forklift, and several huskies.

barbender

The fool gambled and lost.
Too many irons in the fire

moodnacreek

Everything I have is stick shift. I wonder if the time has come when I can leave the key in the ignition like the old days.

Bruno of NH

I often wonder what some of these new trucks would be like with a stick.
I learned to drive on a 78 Chevy with 3 on the tree.
When the shifting linkage didn't lock up😁
Lt 40 wide with 38hp gas and command controls , F350 4x4 dump and lot of contracting tools

starmac

I well remember those days, I used to travel 610 loop around Houston daily, it was rare you didn't see at least one pickup running wrapped out, hung in second gear.

I changed out quite a few of those shift tubes back then too.
Old LT40HD, old log truck, old MM forklift, and several huskies.

barbender

My next truck will be an auto. I've always had manuals, for the fuel mileage and reliability. Well, my 6 speed nv5600 blew a seal and pumped all the oil into the transfer case, and locked up the back wheels (in heavy 60 mph traffic) I was dead in the water. It all happened in th icourse of a 100 mile trip, I never knew I had a problem until she locked up. That repair was $5300 iirc, so the reliability and cost argument kinda went out the window at that point. The newer Dodge Cummins are actually derated with a manual, the autos they have behind them are standing up to the torque better.
Too many irons in the fire

Bruno of NH

I only have a 1/2 ton GMC left 2007
Pulls my 10,00lb dump
One trans rebuild $2,800
5.3 with 3/4 ton rear springs 4.10 rear gear
I like this engine better than the 6.o
Lt 40 wide with 38hp gas and command controls , F350 4x4 dump and lot of contracting tools

UN Hooker

 barbender

          When I build a NV4500 4X4, I always drill a 1/8" hole in the bottom of the  adapter  (between the trans. & transfer case) above the rear mount.  WHEN the trans. seal goes south, 
the oil will end up on the tailgate, looks like the tailgate has chicken pox. That gives you time to crawl under and see whats going on before you get the 5K$  supprize ! 
              UN
Retired Toolmaker/Moldmaker
C-4 & C5D TF - 5500 Iron Mule - Restored 4400 Ford Ind. FEL ex Backhoe w/custom built boom w/Valby 360* grapple w/18' reach - 920 Cat w/bucket & forks w/clamp - Peterson 10" WPF - LT-15 - Cooks Catsclaw & Dual tooth setter - many Husky saws

barbender

UN Hooker, that sounds like a very good idea! My 97 has a NV4500, that granny went to 297K and the countershaft 5th gear retainer pushed off and caused a bit of drama. That truck is pretty rusted out, I don't know if it's worth the effort but I bought the parts so I'll probably cobble it back together.
Too many irons in the fire

firefighter ontheside

Quote from: moodnacreek on February 13, 2019, 06:34:55 PM
Everything I have is stick shift. I wonder if the time has come when I can leave the key in the ignition like the old days.
It's getting pretty close.  I bet none of the younger guys at the fire dept can drive a stick.  The first firetruck I drove was a 1974 Ford.  Had to double clutch it.  I love my automatics, but it sure would be fun to drive my truck with a 6 speed manual.  440 horsepower turbo diesel and a clutch.  Alas, I will just keep driving my automatic and drinking coffee while I start from a stoplight.
Woodmizer LT15
Kubota Grand L4200
Stihl 025, MS261 and MS362
2017 F350 Diesel 4WD
Kawasaki Mule 4010
1998 Dodge 3500 Flatbed

snowstorm

while picking up parts at the ford dealer i asked the service manager what he had for top secret imfo on the 7.3. he did go to a class on it no hp numbers yet. it will be the most hp of any gas motor. he was told a ;little less power than a 6.7 and a little less fuel mileage. i guess time will tell. and that the v10 is going away

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