I have a Terex scraper S7 (1976) with a 471 Detroit in it that is used sporatically to haul clay or dirt. Besides oil leaks and wet stacking when idling the engine ran strong. Not so good any more. Three weeks ago, the temperature guage went to maximum. Coolant was low so I added. That is when I noticed the split in the lower rad hose. Replaced the hose and filled radiator. Everything seemed to be back to normal. Two weeks ago when servicing I checked oil. It was at full mark (normally would be below the add mark) and white slime on dipstick. Coolant was not visible in the rad. Filled radiator. Last week worked engine for 4 hours (idling while loading and then short run to drop load). Next day checked oil and coolant- oil was full with white slime on dipstick and coolant was not visible in rad. Took drain plug out of oil pan. First fluid out was green coolant (2 to 3 litres). After draining oil, I then drained coolant, no trace of oil. I saw some threads that talked about leaking oil coolers. I have removed the cooler and will get it tested tomorrow or Monday. If this is not the problem, the local dealer feels the only other problem would be a corroded piston sleeve/liner or seal between liner and block. Any one out there with any other theories or suggestions?
Cracked head. That's way more common on a Detroit than a cracked piston liner.
Think i would do as willie said and get the head checked but not at that dealer because the 71s have dry liners no seals there and even if it did or the block and liner had a crack it would leak into the air box and out the drain not the oil pan.
See what happens after checking couler,good luck .kerry
I agree on the cracked head.
Thanks for all the quick replies. If the oil cooler is not the problem (get tested Monday), is there a test to make sure that the problem is a cracked head (bubble test, dye, pressure test, etc)? The local dealer I spoke to said that the oil pan could be dropped and then the radiator pressurized to look for coolant coming down. Does this make sense? If needed, where is a good source for a 471 head (Canada, USA)?
We used to pressurize the radiator with the valve cover off first and look for leaks. If that didn't show any, then we pulled the pan.
Another place to check for water entering the crankcase is the water pump itself.On my 4-71 it drives off the blower.
The best advise i can give, is find yourself a Detroit mechanic (71/53 series) You can bet, most likely it will be an older person, like me and Willie59. These engines are very unique to themselves (if that makes sense) and require special tools to set injectors and knowledge to set injectors,rack,governor,etc. Im sure its a cracked head, from you description of events keep us posted and good luck
We ran a bunch of Wabco D's with 471s in them. We had this problem every once in a while The little figure 8 oring on the water jacket between the head and the deck would flip and dump water into the oil. Check those out and also make sure the liners are set to the right height above the block. This seemed to be the problem in a couple of them, after resetting the liners all was good. Hope its an easy and cheap fix for you......Clyde
Placed the oil cooler into a dunk tank today, no evidence of any leaks. From the previous threads it sounds like three possibilities- cracked head, seal on water pump, or o-ring between head and block. To narrow it down, I would like to try some further testing. Filling and pressurizing of the cooling system seems to make sense. However, the neck on the radiator would not accept an automotive rad tester (neck is approx 3 inch diameter with a screw on cap). Any suggestions as to putting pressure to rad? Once the cooling system is under pressure will it be obvious as to where the coolant is going or which component is defective?
John The rad opening on my terex is a screw on cap approx 3-4 inch diameter. What did you use or make to be able to pressurize the cooling system? An automotive rad tester just doesn't do it.
you might be able to get a test plug from a plumming supply store. They are a rubber ball that you can inflate to seal off the neck.
make sure when you buy a replacement head, that you get the same head. Im not sure what you have, but it could be a 2 valve head, but it could be a 4 valve head. Correct me if Im wrong Willie59, but the serial number/model number may not be correct to the internal parts, someone could have changed the pistions/liners/head to a "N" series engine, if it was an older 2 valve head and not changed the number on the block. You could always pull the valve cover and count how many valves per cylinder, also Keep us posted
I use a Stant coolant system pressure test kit with the optional expansion fitting. It is basically a stepped piece of rubber that has a screw going through it. You put the proper step in the bottom of the filler neck and tighten the screw which expands the rubber into the hole. Pump up about 15 PSI of pressure and any leaks will show up right now. Good Luck!
cracked head would show up as bubbles in the radiator , my bet would be cooked head sealing rings or leaking injector tubes .
Where would I find the serial number on this engine? I would like to get as much info as possible before tearing apart.
Wow, it's been a long time since I've worked on these engines Willis, memories are getting real vague, but I do believe you could interchange 2 valve and 4 valve N head. Sorry, I don't have a good pic malcolm, but there should be a flat spot, either toward front or rear of block, just below the deck of block where head sits on block. That flat spot should have two number series, a top line series and bottom line series. The top line numbers are the model number and model specs. The bottom line series is the serial number. As for your particular problem, water in oil, I assume you're saying you're seeing coolant in the oil in oil pan. Going on vague recollections, when you typically have a cracked head, you're going to see combustion residue in radiator, it will even pressurize cooling system. But coolant leaking through crack in head or failed injector cup typically gets burned in combustion, leads to white smoking exhaust. True, when engine is shut off, some coolant from crack/bad injector cup will leak into piston chamber and can possibly leak into crankcase, but that's hard to prove. Like I said, cracked head or bad cup will typically show some evidence in radiator, carbon particles building up on radiator cap or floating on top of coolant in radiator. If you don't see any combustion residue in radiator, I would tend to agree with what was stated by others, either a bad o-ring deck seal between block and head allowing coolant to leach into cam galley, or failed water pump as water pump drives off the blower shaft on a 4-71.
by leaking injector tube i mean in the top under the rocker cover which will leak into the oil only , not into the cylinder onto the piston
I agree Willie59, I guess what I meant was, dont replace a 4 valve head, with a 2 valve head, it changes the HP. Dont ask me how I know
Let me jump in and rule out the water pump there is a drain hole in the housing that lets the water out should the seal let go and it is not sealed to the blower anyway ,Like Willis said dont ask how i know
Unless a dirtdobber gets in that drain hole. :Banghead:Banghead:Banghead:crying:crying I once moved a machine 100 miles home in the freezing rain, and started pulling engine for a dirtdobber and a water pump
Good point why do they never stop up what we need them to ?As hot as this one got it would be a baked dirt dober too..
Interesting conversation at this thread, and I must admit, it's been so long since I've worked on a Detroit I've forgotten most of what I knew. It will be interesting to know what the problem is when malcolm2 finally finds it. :yup
As I recall the two valve heads used a low block which required a standard style head gasket. The four valve heads were for the high block which used the fire rings on the liners and the O rings for coolant and oil. I could certainly be wrong though. Pressurize the radiator and you will see any leakage in the injector coppers right away. Cracked heads as I recall usually pushed coolant out the radiator cap.
LoL, my sentiments exactly John C, been soooo many years since I've worked on those things, and so much misc junk crammed in my head since, I'm doing good to remember anything about them other than recall doing several in-frame overhauls out in the field by myself on the dang things. Oh the good old days.
I recomend as long as the water pump and oil cooler are eliminated, removing the oil pan and pressurising the cooling system as the best way to find your leak. I worked on a 471 that we tore down three times, when I was shown this proceedure, it turned out the top of the liner bores were cracked, appparently reletively common on high hour high hp 471s.
I rebuilt a 671 the other day with a two valve head and it had the fire rings on the liners not the standard type head gasket, sorry to ruin your theory! haha.
Sounds like you could have a cracked head gasket to me, as I have got a sorta similar issue with an Old IHC engine in an old Grader.
I'm sitting here with the identical problem. Head was tested and came back negative on both pressure test and magna flux crack test. Haven't gone further on the problem. Wonder what Malcolm found on his engine?