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1994 Altima timing chain replacement Forums > > 1994 Altima timing chain replacement 1994 Altima timing chain replacement
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Old 01-01-2018, 09:19 AM
christos christos is offline
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Default 1994 Altima timing chain replacement

Car has 205K miles and the noise from the under the timing cover has increased recently. I checked both idler pulleys. alternator, power steering and water pumps and they seem to rotate smoothly. Noise is louder at idle. Most that I read about this engine seem to point to the timing chain guides.

Given the car's age, spending money to have this done at a shop would be more than the car's worth. I do most car work on our cars, so I feel I can handle it.

I have seen a few videos/posts about this job, but none specifically for the early cars such as mine. Not sure if there are differences. I have the factory service manual, which I plan to follow to the letter.

The service manual calls for removal of the cylinder head. However, most videos/posts I have seen do not do that. Is removing the head necessary? That would be a game changer.

At this mileage I think I should replace all timing chain components, what do you think? I am buying all OEM parts, including both chains, tensioners and lower guides. Some aftermarket kits come with new gears, do they need to be replaced (assuming the teeth are fine)?

In the process I will be removing both lower an upper oil pans, which is a good thing since both are leaking. While the service manual calls for a liquid sealant, I have seen gaskets available for both locations. Are they worth using, maybe in conjunction with a sealant?

Any other advice before I start this job? Despite its age I like the car and it has been pretty reliable. It will not win any drag races, but it's a great spare car and I'd like to keep it.

Chris
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Old 01-03-2018, 09:33 AM
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I've done lots of these! Back in the day, it was a pretty common job because the cover would develop a leak near the oil port on the lower side of the cover. Originally, Nissan claimed you had to remove the head and the labor time paid accordingly. Later, they figured out techs were doing it without removing the head (and making good money doing so even under warranty rate), so they adjusted the procedure and time from around 13.6 hours down to around 4.6 hours.
The hardest part of the job is removing and reinstalling the timing cover as there is not much room between the engine compartment and the front of the engine. When you remove the crossmember and right side mount, needed to remove the oil pans, the engine will move forward towards the right side of the engine compartment and there will not be enough room to remove or install the cover. My trick was to get a piece of 2x4 about 18" long. I would jack up from under the engine and remove the side mount. Then, I would place the 2x4 between the right-side, lower control arm and the right side axle. If all goes right, as the engine is lowered, the 2x4 get pinched between the two, supporting the front of the engine and the engine will also tilt a little to the side, towards the radiator. This puts the engine in the perfect placement to be able to maneuver the cover in and out. And remember, you want the cover to come out easy because when it goes back in, it will have sealant on it which you do not want to disturb. The other thing is that because you are not removing the head, you will be re-using the head gasket section that forms the top seal between the cover and the head; this is a graphite-coated gasket, so clean the oil off of it and run a bead of sealant on the top of the cover before installing. As far as type of sealant, I prefer Permatex Ultra-gray Rigid High-torque RTV sealant; you can get this in a squeeze tube or in a cartridge to be used in a caulking gun. It's very similar to the gray sealant Nissan uses and is really good stuff!
There have been cases where the lower, plastic guide has broken on the KA24DE engine causing noise, but these are pretty rare. Most of the time it's caused by debris getting stuck in the oil channels to the oil-fed tensioners. This will cause low chain tension and rattling. If you don't clear out the oil tensioners, you may very well still have a timing chain rattle with the new timing set. For the lower chain, which is most commonly the culprit, remove the lower chain tensioner and the oil filter. Spray carb cleaner or brake cleaner into the oil port that feeds the tensioner until it blows out of the oil filter adapter. If you have access to compressed air, follow it up with blowing out the channel with compressed air.
There was one incident I had where I did this and still had a rattle. I ended up have to take it all apart again. I removed the main gear (the gear that is driven by the lower chain and drives the upper chain) and found a glob of sludge built up behind it. I wiped out what a could and cleaned it up with brake cleaner. Then, I removed the upper tensioner (it may have already been off at that point) and sprayed into the oil port that feeds it until the channel was clear. After putting everything back together, the noise was eliminated. There was also an update Nissan came out with in a TSB to help address this (it didn't really fix the cause of the problem, but did eliminate the noise in many cases). If, when you remove the valve cover, have a chain guide on the top side of the upper timing chain, remove it and the two bolts and discard them. It's not really needed and it eliminates the possibility of the upper chain hitting against it.
Most of the time the gears are in pretty good shape; if you notice considerable wear between the teeth where the chain rides, it would probably be a good idea to replace them. Most of the time they are usually fine. When I could and was dealing with "house money"....meaning "warranty"...I would replaced the front timing cover assembly. The reason was three-fold. For one, scraping off all that old sealant is a real pain! Next, the oil pump is built into the front cover, so, especially with high-mileage motors, it's nice to know you have a new pump. Third, there were some incidents where the oil pressure regulator, which is also built into the front cover, would stick (usually by sludge) and crank the oil pressure up, which could blow out the pressure-side, oil port seal between the cover and the engine block. It's certainly optional to do this.
As far as paper gaskets, I've never used them for this application and I'm not a fan of using paper gaskets with RTV sealant. If the surfaces are clean and the parts are install correctly, sealant works great "as is."
So, in addition to the chains, guides, sealant, brake cleaner, oil and filter...you will need a valve cover set, 11026-01M02 drain pan plug gasket, front crank seal, and the two, oil port seals that fit between the block and front cover. It's also a good time to replace the drive belts, if due, and any bad motor mounts (the one at the rear of the crossmember is a common one that goes bad). Have fun!
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Old 01-03-2018, 10:01 PM
christos christos is offline
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Wow, that is a lot of very useful information, thanks so much! I especially like the trick with the 2x4 to improve access to the lower timing cover.

A few more questions:

- Is there a gasket that goes between the two tensioners and the block? I did not see any in the service manual.

- What are the oil port seals you refer to? I do not see them on the diagram on page EM-17 of the service manual.

- How many new bolts do I need? I see two types, 13075-40F20 (I think I need two) and 13094-40F00 (one). Which of these do I need to buy?

Thanks for all your help! I definitely feel more confident about tackling this after reading your post.

Chris.
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Old 01-04-2018, 01:39 PM
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Actually, there's just one oil port on this engine. The part is Nissan # 15066-5E510 and you can see it on the part diagram linked below, part code "13035H":

https://www.nissanpartsdeal.com/part...p-fitting.html

The update, tension-side guide is # 13085-1E401 and the bolts for it are # 13075-40F20; you need two bolts for the guide.

The updated guide was discussed in TSB # NTB98-055a:

Nissan and Datsun Workshop Manuals > Altima L4-2.4L (KA24DE) (1994) > Engine, Cooling and Exhaust > Engine > Timing Components > Timing Chain Guide > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Timing Cha

Front cover replacement was addressed in TSB # NTB95-058c:

Nissan and Datsun Workshop Manuals > Altima L4-2.4L (KA24DE) (1994) > Engine, Cooling and Exhaust > Engine > Timing Components > Timing Cover > Component Information > Technical Service Bulletins > All Technical Service Bulletins for Timing Cover: >
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Old 01-06-2018, 03:57 PM
christos christos is offline
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Super, thanks so much! The TSBs are extremely useful, especially the updated procedure to remove the timing cover. It's a big job, but now I feel far more confident about it. I will report back once it's done.

Thanks again,

Chris.
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