Oil flushing Bronco engine
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Freshman User
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From: Victoria Canada
Oil flushing Bronco engine
I need to give my Bronco engine a real good oil flush/cleaning as it is showing signs of clogging up. What can I use that will disolve as much as the old gunk/baked on stuff as I can with little/no damage to the engine?
Is there any truth to the rumor that draining the old oil, then filling with diesel fuel and running the engine for 10 minutes will clean it out?
The alternative is pulling the engine and cleaning by hand/soaking... yuck.
thnx!
1989 Bronco, Eddie Bauer
5.8 L v8
~250K km on engine
Is there any truth to the rumor that draining the old oil, then filling with diesel fuel and running the engine for 10 minutes will clean it out?
The alternative is pulling the engine and cleaning by hand/soaking... yuck.
thnx!
1989 Bronco, Eddie Bauer
5.8 L v8
~250K km on engine
Beer Fridge Finder
Joined: Apr 2003
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From: Savannah, GA
Oil flushing Bronco engine
Diesel fuel will clean it, yes... until it detonates. I highly reccommend NOT putting diesel in your oilpan. It can get very ugly. 
Transmission fluid is very high detergent and it will do a fairly good job of cleaning it. They also sell stuff at auto parts stores that can be used for flushing. I've done the tranny fluid gig and it works pretty well.
Transmission fluid is very high detergent and it will do a fairly good job of cleaning it. They also sell stuff at auto parts stores that can be used for flushing. I've done the tranny fluid gig and it works pretty well.
Postmaster
Joined: Jun 2001
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From: Loveland, CO.
Oil flushing Bronco engine
How do you know that your engine is "clogging up?"
I do not recommend those flush products that you see in the auto parts store, except for new engines or engines that have always had it done. If your engine is that gunky, those products will probably do more harm than good. They will either dislodge stuff and clog your oil passages, or cause leaks where previously the gunk was keeping it from leaking; or both.
Transmission fluid might work as a gentler flush, but I'm not sure. I know that back in the day, we used to have someone keep the engine running while we dumped a quart of water or a quart of tranny fluid into the carb and ran it through. This was supposed to get all the carbon off of the pistions etc. I can't honestly say if it worked or not, usually by the time we did this, it was because the engine was shot anyway.
I do not recommend those flush products that you see in the auto parts store, except for new engines or engines that have always had it done. If your engine is that gunky, those products will probably do more harm than good. They will either dislodge stuff and clog your oil passages, or cause leaks where previously the gunk was keeping it from leaking; or both.
Transmission fluid might work as a gentler flush, but I'm not sure. I know that back in the day, we used to have someone keep the engine running while we dumped a quart of water or a quart of tranny fluid into the carb and ran it through. This was supposed to get all the carbon off of the pistions etc. I can't honestly say if it worked or not, usually by the time we did this, it was because the engine was shot anyway.
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From: Victoria Canada
Oil flushing Bronco engine
I had the truck looked over by a 4x4 mechanic after I started loosing oil pressure and he said that hes seen this before, where the oil screen/passages were probably getting clogged up and that I need either a complete re and re or a new engine to get it working up to snuff.
Getting at the oil screen is a b*tch because you need to drop the tranny and raise the engine to get at the oil pan.
The main problem is probably with the oil pump screen at the bottom of the pickup in the oil pan.
Getting at the oil screen is a b*tch because you need to drop the tranny and raise the engine to get at the oil pan.
The main problem is probably with the oil pump screen at the bottom of the pickup in the oil pan.
Beer Fridge Finder
Joined: Apr 2003
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From: Savannah, GA
Oil flushing Bronco engine
I leave the filter on, drain the oil, fill with tranny fluid, and drive about 25 miles or to work and back a couple of times and drain it. It will be very black and YUCKIE! :-)
Postmaster
Joined: Jun 2001
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From: Loveland, CO.
Oil flushing Bronco engine
Unfortunately then I think you need to drop the pan and clean the screen.
How many miles are on it? Iy may be rebuild time anyway, if there is that much sludge in there.
How many miles are on it? Iy may be rebuild time anyway, if there is that much sludge in there.
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From: Victoria Canada
Oil flushing Bronco engine
thnx. I've done one flush already using the standard store bought oil flush products, but I wasn't really happy with the results, as I expected more gunk/crap to come out of the engine.
At the moment, I'm not experiencing any oil pressure problems, but it could come back at any time.
What about the lubricating effects of oil? How does the tranny fluid compensate for that?
At the moment, I'm not experiencing any oil pressure problems, but it could come back at any time.
What about the lubricating effects of oil? How does the tranny fluid compensate for that?
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From: Mountain State
Oil flushing Bronco engine
Hi, I've seen and read about the "clogged" engine for over 40 years now, and it is always from a "mechanic".
Basically, if you havn't changed oil and oil filters reguallary, yes it is clogged, and it needs to be rebuiilt.
Since you are losing oil pressure, the bearings and oil pump are probably shot, the valve seals are done in and the gaskets and seals are shrunk.
Doing anything like running diesel in the oil system, or running 'motor flush' is engine suicide.
right now I'm guessing that the only reason you have oil pressure is from "buildup" of shellac.
By running non-oil products through the engine you remove all of the things oil does....like lubricate the bearings.
Bruce (Big Red Bronco)
Basically, if you havn't changed oil and oil filters reguallary, yes it is clogged, and it needs to be rebuiilt.
Since you are losing oil pressure, the bearings and oil pump are probably shot, the valve seals are done in and the gaskets and seals are shrunk.
Doing anything like running diesel in the oil system, or running 'motor flush' is engine suicide.
right now I'm guessing that the only reason you have oil pressure is from "buildup" of shellac.
By running non-oil products through the engine you remove all of the things oil does....like lubricate the bearings.
Bruce (Big Red Bronco)
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From: Loveland, CO.
Oil flushing Bronco engine
If you are not having oil pressure problems right now, I would not worry about it. Perhaps your flush worked last time.
I would not put anything except oil in your engine now. Like they say, if it ain't broke, don't fix it.
I would not put anything except oil in your engine now. Like they say, if it ain't broke, don't fix it.
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From: Victoria Canada
Oil flushing Bronco engine
OK, sounds like other advice that I had got. I'm currently running a 5.8 (351) in any 1989 Bronco - do you know if a smaller engine can be dropped in? ie: 302? What's generally the best bet, a rebuild, new or getting one from a wrecker?
Postmaster
Joined: Jun 2001
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From: Loveland, CO.
Oil flushing Bronco engine
A 302 will fit right in. But why? Unless you have a hot 302 HO or something, why bother? You won't get any better gas mileage with a 302, and performance will be worse. You could also put an inline 6 in - those are good motors. I'm not sure if you would have to swap the tranny for that though.
Of course a rebuilt motor would be better than a junkyard pull - it depends on how much money you have. If I had the cash, I'd like a Ford Performance crate motor in my rig, but when you add the cost of the stock 111K tranny that I'd blow up with that new crate motor, you're talking several thousand dollars!
Of course a rebuilt motor would be better than a junkyard pull - it depends on how much money you have. If I had the cash, I'd like a Ford Performance crate motor in my rig, but when you add the cost of the stock 111K tranny that I'd blow up with that new crate motor, you're talking several thousand dollars!
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Oil flushing Bronco engine
If you still want a flush, try auto-rx. It is an ester based product, will not strip the engine or destroy the seals. It works over time so it is not a 10 minute flush. Info is at www.auto-rx.com and follow the EXACT instructions.
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From: Victoria Canada
Oil flushing Bronco engine
I've been phoning around here (in BC, Canada) and am thinking that a rebuild is the way to go. The truck still looks awesome and had a new C6 tranny, transfer case and rear end put in last year. Lots of new parts too including good rubber. The engines I've been finding in the wreckers seem to be overpriced (ie: 186,000 km engine goes for $1,000 can)
It looks like I can get a complete re and re for about $2,800.
I'm tending to agree that a serious flush will spell trouble.
cheers
It looks like I can get a complete re and re for about $2,800.
I'm tending to agree that a serious flush will spell trouble.
cheers
Post Fiend
Joined: Nov 2002
Posts: 9,987
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From: Memphis, TN
Oil flushing Bronco engine
My brother-in-law's '93 recently clogged up and we found ~3/4" of deposits in some places inside the crankcase. The local Jasper dealer had a reman block in it 2 days later for ~$3,000 with a 100,000mi P&L warranty.
Last edited by steve83; Jul 14, 2003 at 06:02 PM.
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