The crankcase screw has passed

crankcase bolt

Well, let's go change the oil in our car like so many other times. Everything goes as usual, however, when we go to press the crankcase screwWe realize that something is wrong. A nervousness rises through our body when we realize what it just happened...

At the time of turning something unexpected happened: we are not able to tighten it well. The resistance to turning that indicates that it is firmly attached never quite arrives. what can do that crankcase function of our car is not fulfilled and begins to lose oil. This is a problem that we must solve as soon as possible, because otherwise the damage could be very serious.

How to repair the crankcase thread

Fortunately, this is a problem that we can fix if we are careful and a bit of skill, without the need to fit a new crankcase to our car. In this way we will be able to save a lot of money, since a crankcase is not an economical part or easy to install for someone without experience or adequate tools.

pass the male

What we can do in this case is repair the thread to be able to put a screw. To be more exact, it involves carving a new thread into the metal. In addition, it is also important that the screw that we put later is brand new. In this way we will ensure that the repair we are doing is satisfactory.

To be able to repair the thread of the crankcase screw we must tap the damaged thread, so that it returns to its original shape. There are kits that include several measures that cost about 40 euros or can be purchased separately for less than 10 euros.

Related article:
Motor oil: how do I choose it?

In either case it is much cheaper than changing the crankcase. The material with which the male is made is harder than the original thread. In this way we will not have any problem when drilling. In the next video You can see how to do it easily and simply:

Tips for screwing in a loose crankcase bolt

  • Any repairs under the car must be done safely. Use if you don't have a shop lift.
  • For tap you must choose the measurement immediately above your sump bolt. This way you will avoid eating too much metal from your crankcase, because if you go too far it will already be a useless piece and you will have to change it for a new one.
  • At the time of passing the male, it is important to lubricate it so that the work is done better and in a much simpler way. WD-40, 3 in One or similar can be used for this operation.
  • Put the male completely straight and do it turn carefully, first by hand and then with a wrench. Don't use drills or any other automatic machines, because this should be a tactful operation.
  • When you have completely inserted the male, take it out the same way. That is, manually, slowly and carefully.
  • Clean well to remove any chips that have been left inside. If your finger fits, take them out little by little. Afterwards, you can use the same loosener that you used to lubricate the twist of the tap. Spray it inside abundantly so that it drips and drags as much as possible. NOTICE: It is better that you do not do it as it appears in the video, because the jet can make the chips go deeper. Instead use a spray of WD-40 or similar have a cannula. Insert it completely so as not to push the chips with the pressure of the spray.
  • Then clean the area well and screw in the screw new of the male size. You must never forget to put the gasket that brings the crankcase screw. It is what prevents the oil from leaking out little by little over time.
Related article:
Everything you need to know about motor oil

An even larger thread if the crankcase bolt has gone past

change car oil
Related article:
What is the recommended time to change car oil?

In some cases we have to pass an even larger tap, because the original thread was excessively damaged. In this case, the new crankcase bolt is also must be the same size. If it's smaller, it won't do any good, and if it's larger, we could seriously damage the crankcase again.

[highlight]As a recommendation, it is important don't overdo it tightening the crankcase bolt once we're done. Otherwise we can damage the thread again and ruin all the work we have done so far. Keep in mind that this operation can be done a limited number of times, depending on the shape of the crankcase and where the screw is located. If it is too close to an edge, the thread repair can be done very seldom. It can even prevent it from being done more once.[/highlighted]

Thanks to this repair we can get out of a problem that, otherwise, would take much more time and money to solve. Especially if you take the measurements of your screw before anything else and buy only the tap you need, instead of a kit.

Picture 3 – Bill Abbott


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      Alex said

    Another quick and effective solution (but not definitive) in case you don't have a male tool at hand, is to take a new screw and put holy Teflon on it, place a good layer of wide and thick Teflon that covers the entire thread so that This serves as a bridge between the screw and the crankcase, then the screw is gently tightened to the crankcase until it makes enough pressure to finish (do not over-tighten). It is a very classic temporary and effective solution among mechanics and workshops, Greetings.

      sll88Sergio said

    This is not as simple as passing a male and that's it, what happens to the bits of metal that the male is taking out, by default they will get inside the crankcase?

      Julius said

    You can use this information, before installing the crankcase plug, clean the area and the screw well, and put a little automotive silicone on the thread, install it seeing that the silicone sprouts from the sides of the bolt, then you can add a little more covering the head of the bolt, let it dry for 30 minutes and add your oil... I hope it works for you...
    Greetings.

      mechatronic said

    When you thread, the chip goes to the opposite side to where you advance. To understand it, you can look at a drill bit when you drill and observe how the chip goes up.
    In the case of the carter, when you apply force from the bottom up, the chip you create will go towards the ground and not inside the carter.
    There is also the threadlocker which is a kind of glue for loose screws. Loctite sells a red one and the truth is that it fixes quite well. I have not tried it in any carter but in industrial reducers that reach temperature. They fix the screw very well and also seal it, so there are no oil leaks.

      Jesus said

    Very good video and instructions, perfect, people like that are what is needed, thanks.