Repair Topics / Vehicle Drive Train Rebuild Problems / Vehicle Rear Differential Problems

Vehicle Drive Train Rebuild Problems

Question: 2001 Nissan Maxima mileage: 80,000. I can't get the engine to come free of the transmission, why? I have disconnected everything I can see on the outside but it still won't come free. I am replacing the blown engine myself, or I am trying to.

Answer: First double-check to be sure all the bell housing bolts are removed. The transmission may be stuck on the dowel pins that align the engine and transmission. If so, use a pry bar to pry them apart.

Question:   1966 Mercedes 250 S 6 cyl mileage: 200,000. In 1975 I bought a 1966 Mercedes 250S car. The car ran but it needed engine and transmission work. In 1978, I bought a used 1967 250S engine and transmission and installed them. I kept the 1966 engine because I wanted to rebuild it and put it back in the car. From 1980 to 1984, I installed several used > transmissions of similar vintage, in an attempt to find a good one. Finally, in 1985, I installed a newer transmission that has 3 planetary gears. I am not sure of the year or which car it came from. I was told how to install it by Mercedes auto salvage. They sold me the necessary parts to make the exchange, and I did all the things he said I should do to make it work. It has been operating as installed since 1985, but has never down shifted under load. I hope to get that working too, hopefully it is only an adjustment. The cylinders in the original 1966 Mercedes engine were worn out, but the pistons were still OK, in that, they were installed just shortly before I bought the car. An auto machine shop installed new cylinder liners in the engine rebuilt the connecting rods, ground the crankshafts, and ground the camshaft. When I picked up the engine at the machine shop, in 1982, I was not charged for any of the machine work done on the block. I was charged only for the new bearings, rings, for grinding the crank and camshafts, and for rebuilding the connecting rods. I never did know why they did not charge me for the machine work on the block. I was told then that that was the first time, they had ever put sleeves in a Mercedes and in the process, one of the cylinders seized and had to be extracted and reinstalled. Years later I got back on the project. My old Mercedes recently got too hot and blew a head gasket. I would like to reinstall the original 66 engine. I started assembling the original engine, when the piston and rod assemblies were put in, the pistons protruded above the top of the block about 0.040 inch. At this point, I do not know what happened. Something happened during the previous machine shop operation. Whatever it was, they did not want to tell me, but they also did not want to charge me for a botched up job, so they felt better about whatever they did, or did not do, by not telling me and by not charging me. That company no longer exists. Somehow, I want to save my engine; after all, it does have brand new cylinders, a new reground crank, camshaft, and other new parts etc. I am measuring all my parts, but I do not know what to compare the measurements with. I do not know if the connecting rods are too long; (It’s more likely that they would be too short), or if the block was damaged on the head surface and was milled down until it looked OK. That’s probably what happened, and it probably happened when they pulled that cylinder. In any case, I need to find out what I have. I also want to find out what transmission I have. Before I send this letter, I will look for ID numbers on the transmission. The block depth, oil pan gasket parting line, which I believe to also be the center of the crankshaft, to head gasket parting line: Front - 8.3742” Rear - 8.3738” Average of the two measurements: - 8.374” The standard block depth from AUTOBOOK is: - 8.392” which indicates that around - 0.018” was removed from the block. Where did the other 0.022” of piston protrusion come from? In addition, from AUTOBOOK, minimum acceptable depth is - 8.378”, which is only .004” more than the actual block measurement. Perhaps all I need to do is use a cylinder shim with the head >asket. Some things I am thinking about and things I may need to do: 1. I need to know the stock distance between the centers of the camshaft and the crankshaft. This distance is important because the camshaft sprocket w/timing chain establishes the correct time of opening and closing of the valves. The length of the timing chain is a fixed. Perhaps I can make use of an offset key in the camshaft sprocket to compensate for the timing chain being a little too long 2. The correct deck clearance; to develop the proper compression ratio, perhaps all I need to do is remove 0.040” from the tops of the pistons. I don’t think it’s that simple. 3. Determine the volumes of the head combustion chambers. I just had the head redone. I t was warped from the over heating. The head shop I took it to told me they were going to straighten the head before they ground the valves. This would have reduced some of the problems I am having to deal with now. What they actually did was no straightening at all; they simply milled off enough meat from the gasket surface to make it flat and then made a bunch washers, from aluminum beer can metal, each 0.005” thick, to stick under the camshaft towers. There were 2 or 3 washers under the front and rear towers, enough to allow the camshaft to turn; it was tight, but it would turn. I do not know how important it is, but common sense tells me that the compression ratios of all cylinders will have changed.  The head was crowned enough to require a total of  four 0.005” thick washers, a total of approximately 0.020”, under the end cam towers, in order to enable a more gentle turning of the camshaft. All of this could change when the head is eventually torqued down for the final head installation. The 0.020” shims are only to straighten the camshaft supports; additional shim material will need to be added under all the towers in order to take up the slack in the timing chain. That’s why I need to know the stock distance between the shafts. I have sent a similar letter to Mercedes people several days ago, that should be able to help me, but I have not heard from them. 4. Determine the total head gasket and head shim thickness necessary to create the proper compression ratio. 5. Determine the correct cam pedestal shim to obtain the correct distance between the centers of the crankshaft and the camshaft. 6. Determine the correct valve stem pressure piece thickness to enable adequate valve clearance adjustment. Perhaps there is a simple solution to all this, but I do not want to junk the whole thing. This is not the only question I have, but it is the main question. If I can figure out a way to salvage my engine, I will ask a few smaller questions.

Answer: Here are two relevant generalities that should apply to all engines: First, the clearance between the piston and the cylinder head with the head gasket in place should be no less than .037 inches. If the shape of your cylinder head does not allow for the piston to protrude up inside, then you may have to have the tops of the pistons cut for clearance and the engine rebalanced. Second, we would replace the cylinder head on your engine because it was overheated and warped. We have found that once an aluminum cylinder head is overheated the metal looses its temper. Therefore, if it is used again, it will fail to hold the head gasket resulting in the head gasket leaking.

Question: 2001 Ford F150 mileage: 90,000. What is the difference in a short block and a long block rebuilt engine?

Answer:   A long block is an engine equipped with cylinder heads. A short block does not have cylinder heads.



Question: 2004 Dodge Dakota mileage: 43,000.  Just replaced new short block, before replacing I was getting water in my oil pan.  After replacing the short block, I am still getting water in my pan.  Used the old heads, could I have a cracked head?  Have been working to fix this problem for some time so would appreciate any other suggestions.  Thanks

Answer: It is possible you have a cracked head that is causing coolant to get into the oil pan.



Question: 1998 Chevrolet Camaro mileage: 56,090.  I have a freshly rebuilt transmission. I have put it in 3 times after pulling it out to have the builder recheck it for the same problem.  It is stuck in first gear and will not shift up.  It has reverse and park.  It will not manually shift nor can shift by bypassing the vacuum module (running it up in first gear then shifting manually).  In addition, the governor seems to be functioning properly.  Please help if you have anything else I can try or might have missed, for I am at the end of my rope.  Thanks

Answer: It sounds like you have a transmission control solenoid that has malfunctioned, replace the control solenoid for first gear to repair problem, recheck system.



Question: 2003 Honda Odyssey mileage: 50,000.  My son and I rebuilt the transmission.  Now we have reverse and no forward at all.  In addition, made sure the linkage was shifting the valve.  We even pulled the transmission and took it apart and put it back together again to made sure that we had not put something together wrong.  Everything is exactly as the manual said it should be.  HELP! Thank you for your help

Answer: You might try adjusting the shift bands or you may have a a shift control sprag in backwards. Disassemble to re-inspect, reassemble correctly to recheck system.

Answer:    Changing engine size is a bigger problem than getting the transmission to “bolt up.”  The entire computer drives engine management controls will have to be changed also.  If you have to pass emission inspections in your state, the engine swap could lead to an even bigger problem. We don't recommend it.

Repair Topics / Vehicle Drive Train Rebuild Problems / Vehicle Rear Differential Problems

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