# D21 KA24E blowby



## KrAzY (Sep 29, 2010)

So i have a 1992 d21 HB pickup with the ka24e 2.4 and i recently noticed it having a slight mis when it is idling so figured i would start checking things out and upon inspection while it is running and taking off the oil cap i can hear a pretty good humming and what i have determined to be probably bad blowby. 

I can put my hand over the oil filler cap and feel the air just pumping out of there, I kind of found this to be surprising with a engine with what i considered low miles for a nissan d21 ( only 107k miles on it ) when so many others have gone well over 200k+ But i can only assume it is due to previous owner neglect or abuse of this vehicle. SO i proceeded to remove the plugs to see what they looked like and 3 out of 4 looked pretty good actually but the number 2 cyl plug however has a ash grey chunky built up around most of the electrode, Some broke off with me loooking at it but i have never seen this before and can only assume without a compression gauge that this cyl is the bad one causing the blowby and i thought probably the mis as well. 

But after replacing all 4 plugs and wires it still idles with a mis so my only other idea is to check the points and distributor cap. But my main concern now is is it even worth putting any more money and time into this truck with this blowby? I have read many places that say it needs a rebuild and is basically shot and to get rid of it but other then the slight mis it runs and drives great still and my wife loves this little d21 for some reason. So how long can she continue to drive it with this bad blowby? It seems to be that most products that claim to doe that are a bunch of hogwash but if some one had experience with something that may work i'd be open to try it.

You can see in these images the 1 spark plug i am refering to i tried to get it in focus as well as i could. Any advice would be appreciated i also wanted to know if using engine restore or CerTechGels or any of those types of things that claim to restore compression and solve blowby actually work and would fix the blowby? I know all vehicles have it and as they age have slightly more blowby but i know this is not you're common blowby i am getting lol. I have seen worse on youtube though with smoke or mist coming from the filler cap and mine doesn't do that yet.


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## jp2code (Jun 2, 2011)

Get a compression test kit first, and verify you have an actual problem.

This one is only $25:

Amazon.com: INNOVA 3612 Compression Tester - 4 Piece Kit: Automotive

If you don't have any compression problems, then there is no reason to rebuild the engine.

Engine Rebuild: $800
Compression Test Tool: $25

Hell, anyone could justify a new tool for that kind of coin savings.

Next, pull the codes on your truck to see why it is missing. Do you know how to pull the codes? Here is a video I made to show people how to do it:

https://www.youtube.com/watch?v=6l7SwU7ZuVk

For that one fouled plug, replace the distributor cap, rotor, wires and plugs. Use Genuine Nissan parts if you can. They are not that expensive, and last MUCH longer than aftermarket parts.


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## KrAzY (Sep 29, 2010)

jp2code said:


> Get a compression test kit first, and verify you have an actual problem.
> 
> This one is only $25:
> 
> ...


Thanks for responding jp , I guess i can buy a compression check to verify for sure of course i just figured why spend $25 on something when with this type of blowby it has got to be a bad cyl or 2, I should take a video of it so you can see/hear how much air os pumping out of the oil cap, I have seen worse on youtube vids but my blowby seems pretty bad to me when it pumping that much pressure of air out the oil cap.


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## jp2code (Jun 2, 2011)

So, like in this video?

https://www.youtube.com/watch?v=4GddZqt46gg


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## KrAzY (Sep 29, 2010)

jp2code said:


> So, like in this video?
> 
> https://www.youtube.com/watch?v=4GddZqt46gg


Exactly like the one i am posting, The sound is identicle infact the humming that comes out after ya remove cap fast forward to 1:20 to see it and the same pressure he shows with the paper towel i am getting from oil cap as well.

https://www.youtube.com/watch?v=Qqvjc3DOU44


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## jp2code (Jun 2, 2011)

The guy never says the blow-by is causing any problems, just that it is bad for the engine.

It may or may not be causing the miss you are hearing. It is certainly worthwhile to get a compression test for it. Your local auto parts store may have a compression test tool that they can loan - or they might be able to pressure test for you.

Just be careful doing a compression test on these aluminum head engines. If the engine is hot, it will grab onto the spark plug really tight. When you try to remove it to put the compression tool in and the head is tight, you may wind-up pulling the aluminum threads out or snapping the spark plug off in the head. Try to wait until the aluminum head is cool to the touch before trying to remove any spark plugs.

Personally, I would not trust any local shops to rebuild my Nissan engines. There are too many of them that say they are great but don't know what they are doing on Japanese engines.

If you want to keep the truck for a long time, a JDM (Japanese Domestic Motor) KA24 can show up at your doorstep for $800:

$850: 93 01 Nissan Altima 2 4L Engine JDM KA24 SE XE GLE GXE Complete Low Miles Engine | eBay
Rebuilt $775: 1990 1992 Stanza KA24 2 4L Rebuilt Engine Assy JDM | eBay
$875: 1993 2001 Nissan Altima SE XE GLE and GXE Used Japanese Engine KA24DE JDM | eBay


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## KrAzY (Sep 29, 2010)

jp2code said:


> The guy never says the blow-by is causing any problems, just that it is bad for the engine.
> 
> It may or may not be causing the miss you are hearing. It is certainly worthwhile to get a compression test for it. Your local auto parts store may have a compression test tool that they can loan - or they might be able to pressure test for you.
> 
> ...


Thanks for the engine info may come in handy, I will get a compression tester either from buying or like you said borrowing from autozone or oreilly's or something and check them just to know for sure, I didn't plan on junking the truck or anything anyway my wife loves it even though it is a rusted out/faded and dented ugly thing now lol I don't think i would invest in a new engine anyway, But she says that's why she loves it so much because she doesn't have to worry about some one dinging it or denting it haha but it has been a great little work truck over the years. From what i have read about blowby is that as long as i keep oil in it and changing the oil rutinely and keep up with maintenance it very well may run still for a long time So if i can just get the misfire figured out it may last a long time yet! But i will take off the cap today and check it and the points ect when my wife gets home with it from work. I am hopeful it is just a misfire from a bad distributor cap but that plug in that #2 cyl in the pics i posted is the only one with that buildup on it the other 3 are clean. So am i correct to assume that at least it is probably that cylinder that is the problem with the plug looking like that? The signs sure seem to point to that is the misfiring cylinder.


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## jp2code (Jun 2, 2011)

Yeah, it's probably just that one cylinder where the rings are having an issue. Sometimes rings slide so that the gaps in them line up. It isn't common, but it would cause blow-by if it happened.

Pull the codes to determine your misfire.


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## smj999smj (Jan 1, 2006)

You are always going to have some airflow through the oil cap hole while running due to crankcase pressure. I would definitely do the compression test; a cylinder leakdown test would be even better for testing the rings' sealing abilities. I would also check the PVC system; if that's clogged, it will also cause blow-by.


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