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Detroit Diesel MBE 4000 Essential Diesel Engine Bolt Tightening Torques


MBE4000 Main Bearing Bolts

Caution - stretch bolts refer to manual for limits
step 1 = 100 Nm, 74 lb.ft
step 2 = 200 Nm, 148 lb.ft
step 3 = 300-330 Nm, 221-243 lb.ft
step 4 = + 90 degrees

MBE4000 Connecting Rod Bolts

Caution - stretch bolts refer to manual for limits
step 1 = 100 Nm, 74 lb.ft
step 2 = + 90 degrees

MBE4000 Cylinder Head Bolts

Caution - stretch bolts refer to manual for stretch limits
step 1 = 10 Nm, 7 lb.ft
step 2 = 50 Nm, 37 lb.ft
step 3 = 100 Nm, 74 lb.ft
step 4 = 200 Nm, 148 lb.ft
step 5 = + 90 degrees
step 6 = + 90 degrees

Detroit Diesel MBE 4000 Technical Issues


Detroit Diesel MBE 4000 Cylinder Heads Leaking


Detroit Diesel MBE4000 Cylinder head Bolts are stretch bolts!
The MBE4000 head bolts, because there are stretch bolts, loose their clamping force on reuse, and unless they are strictly within the manufactures stretch limits, should not be used again otherwise leaks will occur.
Stretch bolts, when properly torqued, loose some of their diameter to the stretch, but in correct use are elastic, and if variations in the gasket material or other things occur they keep their clamping force by varying their diameter slightly, but frequently, like breathing. The clamping force of stretch bolts is necessary to retain the inevitable variations of the cylinder head and its composite gasket material deformations due to heat etc. and they automatically keep the necessary clamping force on the head gaskets for them not to not leak.

Steve, BDC, Nov 2017

Info from a Detroit Diesel MBE 4000 DDEC Report


MBE 4000 DDEC stats
Top Speed
Highest recorded speed
96 mph, 154 kph

Current Milage
1 231 371 miles, 1 981 645 kilometers

Fuel Consumption
5.83 US gal/hour, 22.07 liters per hour

Fuel Economy
6.49 miles per gallon, 2.759 kilometers per liter, 36.24 liters per 100 km

Cylinder Head Stretch Bolts v Non-Stretch Studs and Nuts


Replacing Stretch Bolts with standard (non-stretch) studs and nuts

Non-Stretch Studs
Not withstanding the above technical information provided concering strecth bolts, some owners have nevertheless chosen to replace the stretch bolts with non-stretch studs and nuts, which I am told, are doing a good job resulting in a leak-free engine.
Steve, BDC, April 2018

Feedback on Replacing Stretch Bolts with standard (non-stretch) studs and nuts

Greg updated us a year after doing the job as follows: I had the valve covers taken off a month or so ago and according to the very experienced mechanic who did it, there was no evidence whatsoever of coolant leakage. Furthermore, I don't recall having to add any coolant in the past year, and if I did it would have only been a minor amount once, but I don't recall for sure at the moment.
Steve, BDC, December 2018

March 2021 update
Unfortunately, I've got bad news about my MBE 4000. It is not "Old Faithful" as you nicknamed it online anymore, unfortunately. I have been informed by the mechanic shop that the engine block has failed catastrophically.
I just ran across my mention on your web page for the first time tonight. So you might want to take the information regarding myself and my truck down from your site so people will not consider this to be a permanent solution to this problem engine anymore.
It is in a truck shop now. They have pressure tested it and the engine block is leaking. The mechanic is sure it isn't the cylinder liners. During the pressure test, air is coming out the oil dipstick, and other places I think he said. Unfortunately I believe the block is now "trashed", and is not practical to replace. I would just be potentially buying other people's problems.
Unfortunately, at this point I see no alternative than to go back to work as a company driver and sell the truck for what I can get for it.
What originally happened, was what I thought was just a blown headgasket, which was bad enough. But that head also turned out to be cracked. When he checked the torque on the head studs/nuts, all 24 were "loose" compared to what the torque specs called for, some more than others. Whether the studs themselves or the nuts, or both, were loose is impossible to determine.
I believe this allowed the heads to become "loose" on the block. Whether this caused the issue with the block, I don't know, but I suspect it did. Additionally, I have been informed that on this engine, the heads "walk" (move around a little bit) on the block, which I did not know before.


Detroit Diesel MBE 4000 Diesel Engine Specs


MBE 4000 Arrangement, displacement, bore and stroke

Inline 6 Cylinder

12.8 liter, 781 CID

128 mm, 5.04 in

166 mm, 6.54 in

MBE 4000 Compression ratio, weight and electronics

Compression ratio

Weight approx
1030 kg, 2270 lb


MBE 4000 Power and torque

370 hp, 276 kW @ 1900 rpm

450 hp, 336 kW @ 1900 rpm

1250 lb.ft, 1695 Nm @ 1100 rpm

1550 lb.ft, 2100 Nm @ 1100 rpm

MBE 4000 Dimensions
length 1339 mm, 53 in
width 1069 mm, 42 in
height 1130 mm, 45 in

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