How to Replace Main Bearings Without Removing the Crank

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Written By Nicklaus Frost

To get into the procedure, it is essential to loosen all main bearing bolts except big ends approx 1 mm, and you should not make the crankshaft overstress both fronts, rear seal. 

Point out the new bearings if their thrust bearing face is a part of thrust or it is separate half-thrust. 

Probably, you will have to go forward with an action to replace the engine or crankshaft out entirely. If you think the thrust bearing is not worn, please proceed below through our steps, taking the main bearing down that has the thrust to verify the condition.

How to replace main bearings without removing crank?

  1. Before starting replacing bearings process, we shall go through removing bearing caps at a go. 
  2. The first step commands try to remove a cap and note from the bearing shell tab side. It’s located thereby. 
  3. Then, start rotating the crankshaft. An oil hole will be visible through the process. 
  4. The next process is to push something with the thin hard head into the oil hole. To prevent your crank from scratching or jamming on the bearing, using a thin hard head object that, when pushed in, sits low enough to push against without rubbing is necessary. 
  5. The best way to fasten a brake plate with rivets or nails is by using either a clouthead nail. Please turn the crankshaft until your device comes up against the shell (bearing). It is seen on the opposite side of the tab (Mentioned in step 1). 
  6. Slowly rotate the crankshaft by hand with one or two fingers against the shell. This should cause it to start rotating on its own in an attempt at self-assembly. It rotates with the crankshaft. 
  7. After 180 degrees of rotation, the bearing shell falls out. If stuck to the crankshaft, what can you do? To remove it from your crankshaft, you may need to put some metal into its path so that when it tries to re-enter again and break oil’s bond with itself. This will cause more force than needed which should separate them in time.
  8. Select a new shell. Reinsert the new shell in reverse, applying some assembly oil to its bearing surface. Gently ease it past any retaining pins or clips until you feel fit against your crankshaft. Then, apply more pressure as needed while rotating anticlockwise concerning what was faced during removal. This will ease the shell sideways along with the crank journal & help to get the tab lined up to go into the slot. Don’t forget to remove the shell rotation device now.
  9. Well, it’s easy to replace the cap shell now. Be mindful of refitting the cap assembly the same as the start. Torque the bearings up to spec. Repeat the steps in the case. 
  10. Finally, you should reassemble the engine. Plus, remember to fill with oil to the proper level. 

Replace Main Bearings Without Removing the Crank

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When to replace main bearings?

The bearings are likely to go when you start noticing leaks, engine noise, or the engine starts running rough. Unfortunately, crankshaft bearing failure typically leads to major engine repairs that can be costly.

Many people have found it beneficial to rotate the main crank bearings about every 10k miles, but design or regulation does not require this. Crankshaft bearings will typically last between 150-300k miles unless they become contaminated with water, leaded gas mix, oil haze mixture, or other contaminants. 

In that case, excessive play in shafting should be taken as a sign of imminent failure, and crankshaft should be replaced before dirt gets into bearing housings damaging journal surfaces.

Cost to replace main bearings

It’s going to be at least a thousand, with most of that money going towards labor. You’ll have to take apart the whole block, so parts will cost you another couple hundred or so…

How do I know if my main bearings are bad?

Engine bearing failure is a common issue with vehicles, which can lead to many tell-tale symptoms. Once your engine starts exhibiting these signs, you should have it checked as soon as possible by an automotive professional for any necessary repairs or replacements to be carried out safely without risking further damage. 

There may be some friction on the bearings if you hear a knocking sound from under your hood when starting up an engine. To fix this problem, most people will need to replace their car’s crankshaft pulley. 

Oil pressure is a crucial factor in engine performance. It not only ensures that you have enough fluid for lubrication but also prevents damage by providing an extra signal when something goes wrong with the bearings, rods, or valve train of your car. If you notice any decreased oil pressure at all while driving, then it’s best to get this checked out quickly as lack of grease can directly lead back towards failure.

Final thoughts

The main bearing sleeve rides on top of the crankshaft journal and has oil holes that lubricate it. The sleeves can become pitted or galled when it isn’t enough for them to soak into because this will cause premature wearing out with normal use over time. 

However, in some cases, you may also have bad bearings if none are worn out yet, such as Racing Engines, where higher speeds might make those factors more apparent than usual. 

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