More 8V71 Questions

[buddyten]

Hello Friends:
A couple weeks ago, I posted questions about our 8V71 rebuild/blower issues.   We have now determined that we are going ahead with the in frame rebuild, according to our mechanic.

One of the questions we posed was the use of aftermarket vs Detroit rebuild kits.   Obviously, the Detroit parts are preferable, but are double the cost of using aftermarket parts, which we can secure through Truck Pro.   We understand all about the warranty issues (although Truck Pro states the aftermarket parts have a 2 yr warranty).

Several of you responded with your thoughts and opinions, and we appreciate all the help and input.   Some indicated they would use nothing short of the Detroit parts, and some indicated that the aftermarket parts were OK.   Some made it sound like that if we used aftermarket parts, their failure was somewhat imminent.

Without going into all the explanations we made during our other post, cost is of an obvious concern to us.   If it is almost certain that the parts will fail, then we would be stupid to go with anything but Detroit parts.    If, as some indicated, the aftermarket parts would be sufficient, then we would want to use them for financial reasons.

If the aftermarket parts are so bad, why would reputable dealers like Truck Pro risk carrying them?    I spoke with a local 3 bus charter company, who said they had rebuilt all three of their engines using aftermarket, and had never had an issue, with 2 of them approaching the 200K mile mark.

We are confused....Please help us with our questions.

Thanks again,

[TomC]

It's not so much whether the parts are directly from Detroit or from a reputable rebuild supplier, the real trick is finding a qualified shop/mechanic that knows how to fit the cylinder liners properly, knows how to measure the block so the cylinder liners fit properly, then how to install the rings on the pistons, and the pistons in the cylinders.  Then assembling the whole engine, tuning and making it run properly.  Yes a well put together 2 stroke should run 500,000 miles before overhaul.  But-the 2 strokers are not like the 4 strokes-there are a lot of innuendos that you have to know to assemble the 2 stroke engine.

To give an example-I bought my bus with 64,000 miles on the inframe (the bus company replaced the speedo to easily keep track of the engine mileage).  At 70,000mi, I was having heating problems.  Pulled the engine apart, and yes there were new pistons and cylinder kits, but the cylinders were not fitted tightly-hence not good heat transfer to the coolant.  And the block cylinder bores were warped from the heat.  I had the cylinder block bores over bored by .020", then had new .020" outside oversized inside standard cylinder liners properly installed.  Used the same pistons with new rings.  Amazing how much hotter the coolant ran now that the heat was being properly transferred to the coolant and not overheating the heads and blocks.  I also had to replace one cracked cylinder head.  Still running well to this day-now that it is also turbocharged with air to air intercooling.  Good Luck, TomC

[luvrbus]

Buddy, your situation is totally different than mine I use DD parts I don't like the price but I pay anyway for 1 reason if the parts fail I know they will be replaced by DD plus the labor.  

A DD dealer will repair it on the road if I didn't screw it up if I did then I pay lol You have your shop to fall back on if aftermarket parts fail your bus will go back to that shop.

I just have had no luck getting the aftermarket people to pay for anything so I don't use them plain and simple.  

Stewart and Stevenson a huge DD dealer will rebuild a 2 stroke with aftermarket parts (in frame only) if you request it to save money one of the very few that will but will make it very clear they are not going to stand behind the labor if a part fails

The labor is going to be the same for DD parts or aftermarket that will not change and you are right the aftermarket parts do have a 2 year warrant vs genuine DD 1 year warranty.Your supplier will make a few bucks selling the aftermarket vs the DD parts

I pay 1380.00 for a inframe kit for a 8v92 from FP I pay 3800.00l (probably more now) for a kit for a 8v92 from DD and your guy is going to pay the same from DD then he has a markup  

The aftermarket will work good for you since you are planning on selling the bus I don't use them unless the owner wants it then I buy aftermarket so far I just had one problem and they blamed me which was BS the wrist pin pulled the skirt off the piston.

DD parts fail also I lost a cam in a 8v92 in El Paso it destroyed the engine the cam had a casting flaw DD picked up the whole bill I didn't even have to pay for oil over a 17,000 dollar bill, that is the reason I love my DD parts moral of the story do what your pocket book allows but buy good aftermarket parts not junk 

TomC is giving you some good advice if you see the guy using a block of wood and a hammer installing the liners in a 8v71 you will have a engine die  a early death

good luck

[junkman42]

DD does not manufacture the parts that they sell!  They outsource every last one of them.  Perhaps someone here might know who supplies bearings and cylinder kits to DD.  The over stressed military engines use parts probably from the lowest bidder and contrary to the opinion of some here they do not blow up once a week.  Regards John L

[luvrbus]

John the military buys only OEM for all their engines Cat,Cummins,DD or whatever engine, why do think the DD parts went through the roof when all the stuff in the mid east started parts doubled in price and were hard to come by for a couple of years

good luck