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Timing belt ('96 xj 4.0)
- Thread starter blairboyd
- Start date
- Location
- La Habra, CA
It's a timing chain... But there's nothing in the Haynes either that mentions replacement intervals.
Willis
NAXJA Forum User
- Location
- Hoquiam, WA
Ya, it's a chain. I don't think there is any type of replacement interval, but mine was very sloppy at 145k.
Steve
Steve
5-90
NAXJA Forum User
- Location
- Hammerspace
Yep, it is and always was a chain.
You can check by pulling the distributor cap off (don't disconnect anything, just expose the rotor) and turning the crankshaft manually. If it turns more than about 5* (IIRC) before the rotor moves, the chain wants to be replaced.
There is no mileage interval for chains - you check them manually. However, the 60-70kmile figure that is used for belts is pretty paltry compared to a chain (I've heard of 400-500kmiles on a chain, on quite a few engines...)
5-90
You can check by pulling the distributor cap off (don't disconnect anything, just expose the rotor) and turning the crankshaft manually. If it turns more than about 5* (IIRC) before the rotor moves, the chain wants to be replaced.
There is no mileage interval for chains - you check them manually. However, the 60-70kmile figure that is used for belts is pretty paltry compared to a chain (I've heard of 400-500kmiles on a chain, on quite a few engines...)
5-90
- Location
- Terra Firma
I'm at 240,000 miles with the original chain on my '88. Others have reported 300,000 and more (there's a thread going on this topic right now, I believe on the Non-Tecj forum).
I think you have nothing to worry about. The chain is steel, both gears are steel. The chain isn't likely to break, and it will take a LOT of stretch before there's any likelihood of jumping time.
I think you have nothing to worry about. The chain is steel, both gears are steel. The chain isn't likely to break, and it will take a LOT of stretch before there's any likelihood of jumping time.
Matthew Currie
NAXJA Member #760
- Location
- Vermont, land of big clay
Eagle said:
I'm at 208K, and my 87 went well past 235K on the original chain. I ignore it, and assume I'll hear it clanking against the cover before it jumps.
AZ Jeff
NAXJA Forum User
- Location
- Gilbert, Arizona
RINGKONG wrote:
this topic begs the question.
is the 4.0 a interference engine? chain breaks and valves and piston meet?
*************************************
Allow me to respond with a number of points here:
1. The 4.0 is a pretty primitive engine by modern standards. Sure, its' got 7 main bearings, and decent flow thru the head for a pushrod engine, but it's still 1960's technology, from a mechanical perspective. Since MOST of the more "primitive" engines DO NOT have an interference situation between the valves and the head, I would not worry about this issue, even though I am not positive about the clearances in the 4.0.
2. Timing CHAINS RARELY BREAK. Their failure mode is to JUMP TEETH on the sprockets.
3. If, somehow, the timing chain WERE to break, the failure would be REAL IMPRESSIVE, as the chain would "ball up" around one of the sprockets, resulting in broket sprockets, and/or a broken timing chain cover. Bent valves might be the LEAST of your worries. In any case, this type of failure is merely theoretical, as chains always STRETCH and JUMP FAR BEFORE they BREAK.
this topic begs the question.
is the 4.0 a interference engine? chain breaks and valves and piston meet?
*************************************
Allow me to respond with a number of points here:
1. The 4.0 is a pretty primitive engine by modern standards. Sure, its' got 7 main bearings, and decent flow thru the head for a pushrod engine, but it's still 1960's technology, from a mechanical perspective. Since MOST of the more "primitive" engines DO NOT have an interference situation between the valves and the head, I would not worry about this issue, even though I am not positive about the clearances in the 4.0.
2. Timing CHAINS RARELY BREAK. Their failure mode is to JUMP TEETH on the sprockets.
3. If, somehow, the timing chain WERE to break, the failure would be REAL IMPRESSIVE, as the chain would "ball up" around one of the sprockets, resulting in broket sprockets, and/or a broken timing chain cover. Bent valves might be the LEAST of your worries. In any case, this type of failure is merely theoretical, as chains always STRETCH and JUMP FAR BEFORE they BREAK.
RichP
NAXJA Forum User
- Location
- Effort, Pa
Kinda rule of thumb here, but you only generally replace timing chains and gears when you rebuild the engine, they last that long and it's just a smart thing to do just like putting in a new oil pump. Unlike a chevy 350 with the nylon gears, then it's a 50-90,000 mi thing just like a belt...
- Location
- Terra Firma
RichP said:
Oops ... nylon gears.
That just reminded me ... I DON'T have 240,000 miles on my stock chain. I've been accustomed to AMC V-8s, which also ran nylon teeth on the cam sprocket, and so when I went over 200k on the XJ I assumed I was living on borrowed time and bought a timing set. Got the engine opened up and found (a) all steel gears, so no need to worry; and (b) the original chain was so tight you could hardly tell which one was new. As long as I had it open I threw in the new one, but I saved the old one and would not hesitate to put it into a beater.
Apologies for passing on erroneous info.
8700XJS
NAXJA Forum User
- Location
- California
As long as we WERE talking about timing chains... How much "stuff" do I have to pull off to change my recently found little wet spot where the timing case cover meets the oil pan? I have the FSM as a good reference but it doesn't say anything about pulling the RAD or grill. Do I need to?
TIA
8700XJS
2000 Sport 2X4 (lift free)
TIA
8700XJS
2000 Sport 2X4 (lift free)
