It is however, nearly impossible for an engine to ingest enough water into the cylinders through a blown head gasket while it is running to hydrolock the engine as such little water will simply form steam and exit through the exhaust port during the exhaust stroke.
However, if engine coolant continues to leak into the cylinder s after the engine is shut-down as in the case of the above engine, and then the engine is cranked by the starter motor with coolant in the cylinder s , hydrolocking of the piston s and damage to the connecting rod s , is more then likely to result.
In addition, the crankshaft will likely suffer twisting damage and may break. Many of the 8. Like many other 8. Thorough examination should reveal whether or not a block is too damaged to rebuild. Unfortunately, many engines that are so damaged that they are unrebuildable have been rebuilt and have consequently suffered early, if not immediate, failure.
Most experienced mechanics consider rebuilding an 8. The shorter the piston skirt, the greater the wear experienced by the pistons, the rings and the cylinder bores. As shown in the 4-Stroke Cycle diagram above, the piston is forced against the side of the cylinder yellow arrows by the angle of the connecting rod to the crankshaft rod journal.
Generally, the less lubricated surface that the piston can provide against the cylinder, the greater the wear will be on the components. Also, the shorter the piston skirt, the greater the tendency for the piston to cock in the cylinder bore resulting in greater uneven wear.
High compression engines, especially diesel engines, should have longer piston skirts to endure the higher side loads on the pistons and cylinders.
Compare the length of the short-lifed 8. Longer life engines typically have piston skirts at least as long as the cylinder bore diameter. The ci 5. Also note how the actual contact surface of the 8. The skirt is also cut-away to provide clearance for the rotating crankshaft when the piston is near bottom-dead-center BDC which allows for a shorter connecting rod.
This also made the engine lighter and cheaper to build. As a consequence the 8. However, because of the 8. Also compare the distance from the crown of the piston to the first compression ring on the 8. The distance is much less on the 8. Note the wear and damage to the 8. This picture is found in the 8. In fact, they actually miked within new part specifications. The brochure does not make mention of any initial pre-build micrometer measurements. Without these initial measurements, no valid projections can be made.
The specifications are a range. If the component was measured to be at one end of the range when first installed and is now found to be at the other end of the range at 3, hours, the rate of wear would be considered very high and the life expectancy very low. This is also true of the piston rings, connecting rod bearings crankshaft main bearings and several other components clearly shown in the brochure.
No competent mechanic would reassemble this engine with any of these badly worn and damaged components. Oil pan has been removed.
Unfortunately, the 8. Note how narrow the crank webs, counter-weights, main bearings and connecting rod bearings have to be to fit on the short 8.
The pistons and connecting rods for one bank have been removed and the narrowness of the rod bearing surfaces on the crankshaft can be clearly seen.
The connecting rod bearings and crankshaft show serious wear and scoring, indicating imminent rod bearing failure. Also note the discoloration of the crankcase indicating that the crankshaft, bearings, etc. Unfortunately, in the case of slip-bearings commonly used in 4-Stroke Cycle engines including the 8. The broad radius helps prevent the crankshaft from cracking at the transition from the horizontal journal bearing surface to the vertical journal shoulder.
V8 Crankshaft and Connecting Rod with the narrow bearing shell highlighted in red. Without an adequate oil film to keep the metal surfaces of the crankshaft and bearings properly separated, they will suffer erosion of the metal surfaces or worse yet make contact with each other causing metal transfer and scoring the surfaces, making bearing failure imminent.
This damage can be clearly seen on the bearing shell shown below that was removed from the engine pictured second above. Note that the wear is slightly more pronounced on one side of the bearing towards bottom of picture suggesting that the connecting rod is slightly bent.
When checked, the rod did prove to be slightly bent, probably by hydrolocking of the piston sometime in the immediate past. It is not uncommon for an engine to suffer this damage after a blow head gasket causes Hydrolocking.
If an engine has suffered this hydrolocking damage after a blown head gasket, and this damage is not discovered and just the head gasket is replaced, the engine is obviously doomed to catastrophic bottom end failure.
An engine oil analysis indicating elevated glycol, lead, copper and iron would predict a failure from hydrolocking bottom end damage caused by a blown head gasket. These narrow bearings are also more susceptible to damage from fuel deluded engine oil. Fuel from a leaky injector, injection pump, or fuel lift pump that enters the oil sump and deludes the engine oil will thin the oil so that it cannot maintain an adequate film between the metal parts and a bottom end failure will ensue.
An engine oil analysis indicating elevated levels of fuel, lead, copper and iron would predict a failure from fuel deluded engine oil bottom end damage. A crowded crankshaft: Even though the connecting rod pins on a V8 crankshaft are the widest journals on the crank, when assembled the V8 crank will have two connecting rods crowded onto each rod journal leaving little room for each individual rod bearing.
V8 Crankshaft with Two Rods assembled to each rod Journal. In the picture third above and the illustration below, it is easy to see how narrow the rod bearings of an 8. Note the two oil feed holes per rod journal one for each connecting rod. In a fully pressurized lubrication system like the 8.
Oil tends to exit narrow bearings much more quickly. The wider the bearings, the more oil they can hold longer between the metal surfaces of the crankshaft and bearings, hence wider bearings can carry higher loads. The larger the cylinder bores, the longer the crankshaft and therefore the more room available for wider bearings.
Unfortunately, for the 8. This rather crude Do-it-yourself procedure can easily result in very poor bearing journal surfaces that can cause early bearing failure. A qualified crankshaft machinist with the proper equipment able to perform quality resurfacing has the best chance of providing a satisfactory bearing journal surface. On the 8. Crankshaft main bearings will be discussed in more detail a little later. Another issue with any small V8 crankshaft is the narrow crank webs which are much weaker and consequently much more prone to cracking and breaking as shown below.
V8 Crankshaft with broken web near front end of crankshaft left. By comparison, the inline 4-cylinder crankshaft below which will have only one rod fitted per journal when assembled will have much wider rod bearings. Note the much wider main bearing journals which will accommodate much wider main bearings. Also note the wider and much stronger crank webs between the bearing journals. This crankshaft is from a cubic inch displacement engine, which is less then half the displacement of the cubic inch 8.
Detroit Diesel 4-cylinder 2-Stroke Cycle crankshaft. The inline 4-cylinder crankshaft shown above has 5 main bearings. The crank webs, and the width and diameter of the main and rod bearings have been optimized to carry the stress and load of a high compression, high output engine. By comparison, the V8 crankshaft has the same number of main bearings for twice as many cylinders, and the V8 main bearing journals are much narrower. You can see how crowded a small V8 crankcase can be in the picture directly below.
Notice that the main bearing journals of the V8 crankshafts shown in the illustration and pictures above have been increased in diameter to increase the bearing surface in an effort to compensate for their narrowness.
This is why inline engines with the wider bearings, stronger crank webs, and main bearings between each cylinder, can be air charged e. Air-charging these stronger inline diesel engines can also enable them to run cleaner with fewer emissions as explained in our articles Fuel Fundamentals and Selecting the Right Diesel Engine for Your Boat.
Engines with longer piston strokes have the advantage of typically producing much higher torque at slower crankshaft speeds RPMs. Besides allowing the engine height to be lower, the shorter stroke also has the advantage of reducing the load on the crankshaft main bearings, however the load on the rod bearings is higher. Unfortunately, as bearing surface speed increases, bearing wear increases and so does the risk of bearing failure, especially in the case of the narrow bearings used in the 8.
The above comparisons show why smaller V8 engines that lack the space for the wider crankshaft bearings and stronger crank webs are not capable of the higher power outputs of comparable displacement inline engines.
These are some of the main reasons why most engine manufacturers have abandoned building small V8 diesel engines for use in the more demanding applications such as marine service, and have embraced inline configurations especially the turbocharged 6 cylinder inline with 7 main bearings such as the Cummins B and C series engines.
None of the small V8 diesel engines, such as the Ford and GM pickup truck engines, have successfully achieved reliable service as marine propulsion engines. Tuning-up the engine, especially adjusting the injectors, is complex, time consuming, and requires special tools which are becoming more and more scarce.
This manual is available to current Academy members for viewing from our Academy Library. The complete procedure is described in that section 14 of the manual including the special tools required.
Several of these tools are no longer available from GM or Detroit Diesel, but most can be fabricated. It would be much more convenient to find someone knowledgeable and experienced in the procedure who already has the proper tools, but this is proving more difficult with each passing day.
The above service manual also contains sections on Preventive Maintenance and Trouble Shooting that can be very helpful. Quality replacement parts are becoming scarce and more expensive.
New major parts ie blocks, heads, crankshafts, etc. Because of these recognized inherent weaknesses, Detroit Diesel never did set up the 8. Fortunately, in a vehicular application, the engine is rarely operated at higher speed and power output for very long, usually just during acceleration and when climbing hills.
If the 8. This is why some truck operators have experienced few if any problems with their 8. Since the practice of routinely running at full throttle flank speed to blow out the carbon soot is NOT recommended with the 8. But adding fuel additives that help keep fuel injectors clean and reduce carbon buildup can be quite helpful.
Like many 4-Stroke Cycle engines, the 8. Detonation is the phenomenon when the heated gases from combustion expand in the combustion chamber faster then the speed of sound and generate a supersonic shockwave. Detonation in a cold engine is the result of the increased ignition lag-time that unfortunately, delays ignition until the combustion chamber has an overabundance of fuel. Once ignited, the large quantity of fuel burns too fast, generating a shockwave.
Typically, the larger the cylinder, the lower the frequency. When detonation occurs in the 8. Starting any diesel engine, but especially an 8. Heating the engine or the incoming air reduces the ignition lag-time, avoiding detonation. Detroit Diesel made the mistake of providing a cold weather starting fluid injection canister as an option on the automotive and industrial versions of the 8.
Of course it proved to be detrimental and many 8. The starting fluid device was never offered for the marine version of the 8. Why are volatile fuels such as starting fluid, gasoline or propane so dangerous in diesel powered vessels?
Well remember that electrical devices such as relays, generators, alternators and starter motors on gasoline fueled inboard engines are required to be ignition protected, but most diesel inboard engines are not required to have electrical equipment designed with ignition protection and therefore can provide an ignition source such as a spark that can result in an explosion and fire.
Keep them clear of any obstructions. Also keep the raw water pump impeller, the heat exchanger, the engine coolant antifreeze , the pressure cap, all hoses, and the engine belts and pulleys in good shape. The exhaust mixing elbows on wet exhaust systems should be routinely checked for deterioration and clogging. Due to the poor design detailed above regarding head gasket failures, even the slightest overheating can result in serious consequences. Consider retrofitting the engine with the larger head bolts and later, stronger head gaskets.
Fluid analysis of the engine coolant and engine oil can help detect a leaking head gasket and can also help determine the extent of other internal damage. The injector markings may NOT indicate that the injectors have been drilled larger for the greater fuel delivery required by the higher rated engines.
This can result in some or all of the injectors delivering too much fuel for the lower rated engines or too little fuel for the higher rated engines. And yes, your engine may have already suffered this injector mismatch. Ensure that the engine oil is properly maintained. See our webpage on engine oil. Always shake or stir the new oil container to mix the new oil before pouring the new oil into the engine as the oil and additives tend to separate over time.
This is especially true of larger containers of oil such as drums which must be stirred routinely to mix the heavier additives like zinc that have settle to the bottom of the drum. Always maintain the proper oil level in the engine.
Always replace the oil filter during every oil change. Then cut open the old filter and check it for metal. See our webpage on Inspecting Oil Filters for metal. Always use a quality oil filter. Consider fitting the engine with a by-pass oil filter in addition to the original full-flow oil filter. If the engine sits dormant for long periods, consider fitting a pre-oiler to the engine to pressurize the oil galleys and fill the bearings before starting the engine. This practice reduces wear during startup, which is considerable especially in the case of the narrow 8.
Pre-oilers are often fitted to commercial engines to reduce startup wear. Ours is a water truck with gal tank 5sp 2 sp and we run it hard. For a fleet motor, meh. Like someone mentioned, it was Detroit trying to make a 4 stroke with old 2 stroke technology. If you can find parts why not. I had a real nice C70 with I believe the horse turbo 8.
Pulled a big enclosed race car trailer with it for several years. Never any trouble and actually pulled decent for the time. The fuel truck driver hated it because of the lack of power, but liked that he did not have to plug it in when he took it home at night. He had been promised a new truck when that truck died, so he let it idle continuously during the day and hammered the daylights out of it when he drove it.
His wife would not let him idle it at night because it made their whole house stink! But even trying as hard as he did that 8. They love it because if it has enough battery to flop over it starts. But as described above, finding someone knowledgeable about old Detroits is going to be difficult today. One pinhole in a brake line and voila, no brakes!!! A real boat anchor lol!
Actually, the Toroflow was a Good engine compared to the 8. The one I drove for about a year was an O-K engine when it ran on all 8 holes, but it would drop a cylinder about every week or two till it was only running on 4 cylinders, then it would go to the shop for a week or two. I never added any oil, and it never diluted the oil with fuel or water.
When I switched to the IH FleetStar cid gas V8 and straight 5 spd I got around 3 mpg running same exact trailer, same roads, same loads.
But the 8. The local delivery straight truck this guy had had a DV, They shot it up with starting fluid one morning when the boss's kid forgot to plug it in one night, it didn't like it, blew up shortly after that, and he rebuilt it! Dad has a 79 Ford grain truck, I can't remember if it's a or an , has 13, miles, juice brakes. He wanted to redo the brakes on it a couple years ago since it sets so for so long in between use.
He bought new shoes hardware kits, wheel cylinders I think 2 per wheel? Him and I both were surprised at how easy they were to get. Now if we went to the local truck parts store, we would have been out of luck, we have a very good local parts store.
We had one in the school bus fleet years ago, the mechanic remarked that it was good on fuel They must've bought it fairly new because I always remember that truck. Got a 8. I don't think they ever had any trouble with it. We used to use it every so often and I can say it will run away from our C70 We got 2 's and they motor along good, but the 8. Actually we got a GMC with 8. It doesn't get used a whole bunch but I don't think it has ever given troubles.
Smoked bad when cold and darn juice brakes on the truck. You can post now and register later. If you have an account, sign in now to post with your account. Paste as plain text instead. Only 75 emoji are allowed. Display as a link instead. On the other hand, the Turbocharged Fuel Pincher has a gross output of horsepower at 3, RPM, and has a dry weight of 1, pounds. Both engines are capable of producing up to foot-pounds of torque, depending on their usage. They were also made with a dual full-flow oil filter, a fuel oil filter and a fuel oil strainer.
The cooling system is composed of an air cleaner, a governor and a fan. Both engines also come standard with a starting motor and an oil cooler.
Replacement parts and overhaul kits are widely available for the 8.
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