removing injectors from engine

Jul 2019
Hi everyone

Thanks for letting me join your forum and firstly a confession.

I was never really that good at chemistry at school (i found it one step removed from magic) but i have a problem that might be solved by chemistry so i thought i would try here.

Modern cars (particularly diesels) have problems with the steel fuel injectors becoming locked in place in the aluminion head by a combination of corrosion and (i suspect) heat welding.

They should pull straight out of the top of the engine but instead they manage to bond themselves so tight they can withstand literally tons of pressure trying to remove them.

The only thing i have seen similar strength is cold baked beans (after no one has washed up for two weeks).

But anyway i wonder if anyone has any ideas for any chemical (or chemical combination) that could possibly aid removal.

WD40 and similar fluids have minimal to no effect.

Or has anyone got any other ideas of how they could be removed, i have considered trying to apply vibration (as steel and aluminion would oscillate with different rhythms) but have no idea how to apply the vibration which makes that plan a bit of a none starter.

Very grateful for any help or advice you could give me


Sep 2018
You could perhaps try differential heating/cooling.
It is possible to get freezing spray cans (for example used by plumbers to produce an ice plug in a section of piping to seal it while a joint is being fixed)
by cooling (just) the injectors (without cooling the main engine block) they will shrink (fractionally) relative to the main block, which might then allow them to be removed more readily.

Note that this is just my guess, I accept no responsibility or liability if it causes damage!
I suggest you find a friendly garage mechanic who can tell you how the professionals do it.
Sep 2018
I was chatting to my brother (who has been a car mechanic, amongst other things) and he agrees that the idea of differential heating/cooling should help.
Perhaps heat the block up, possibly with a hot hair dryer, or a (not too fierce) paint stripper.

He also said that WD40 is (by far) not the best penetrating fluid available (just the most efficiently advertised).
he suggests getting a better penetrating oil, and building some kind of cup around the injectors.
Fill this cup with the oil and then leave it to soak in overnight.

Note that these cups could also, then assist in the differential heating of the block verses cooling of the injectors,
shielding the injectors from the heating.
I might be a bit wary of cooling hot aluminium too rapidly (since this could cause thermal stresses, which could damage it).

How are the injectors held in?
Is it just an interference push fit, or are they screwed in, or...?
What sort of hold can you get on them?

If it is just a push fit, could you make some kind of "puller",
(something which pushes on the block and pulls on the injector in response to you winding a nut along a thread)
which would allow you to gradually and gently apply a large force?

A professional mechanic would (probably) have a specialist tool for the job.
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