Timing chain skipped when oil pressure dropped and hydraulic tensioner lost tension (1 Viewer)

[2slo]

Hi there, I'm hoping I can pick some of your brains. I have a locked 97 LX450 with 150k on it. I was messing around on a very very steep dirt hill trying to climb it (testing out there lockers The engine was close to, but below, redline. I think the angle starved the oil pump, the pressure dropped and the tensioner let go allowing the chain to skip back and retard the timing and do generally bad things. The cam position sensor came on and unfortunately this appears to be the reason why. So my questions are:
Does this sound plausable?
Are there other failure points that would have caused this to happen (my oil pressure gauge would drop at very low rpm but then raise right up)?
While I'm replacing the chain and tensioner and probably removing the head what other parts should I replace to improve reliability and peace of mind?
Thank you, I know there are some really smart knowledgeable people on hear and I'm looking forward to seeing what I learn. I appreciate your generosity.

 

[Kernal]

Has the crank pulley ever been removed to replace the crank seal or oil pump cover O-ring, then put back on??

What did you mean "the cam position sensor came on", did you get a MIL light and engine code?

What were the other "generally bad things", loud noises, engine not running, flames or sparks??

 

[2slo]

The bad things were simply the stretching of the timing chain and the skipping of some teeth. So it was actually the best case in a bad situation. Most any other alternative would have been an easy fix (bad camshaft position sensor/broken distributor causing CEL and associated code). The engine never stalled and there was no ticking or any other out of the ordinary sound. I did lose about 3/4 or more of the power, buy I ascribed this to going into limp mode. This led me to think that I didn't "bend" any metal in the engine. The tone of the exhaust note did change, particularly at idle and low rpm where it lost the most power.

About the service history: It looks like it had a new head put on it. I had the car baselined at a recommended shop in Boise before I bought it. (I live in Spokane but I got the truck there).
I am going to call tomorrow and to find out about the crank pulley and crank seal or oil pump o-ring. This thing got progressively too complicated for me so the truck is now in the shop of a sharp and honest mechanic. But he's not a Land Cruiser guy. I just want to move forward in the way that makes the most sense given what we have here.

 

[Rivman1243]

So did you find out what happened?

 

[2slo]

What happened was I bought a used car with no service history. Seriously though... After the weekend. I'll keep you updated, Kernal has been an awesome resource and he pm'd me with some tips. I'll keep you updated. I couldn't find anything when I searched so the thing I got going for me it's that I can inspect the vehicle, but that's not that useful without your knowledge, so thanks for sharing.

 

[math]

What happened was I bought a used car with no service history. Seriously though... After the weekend. I'll keep you updated, Kernal has been an awesome resource and he pm'd me with some tips. I'll keep you updated. I couldn't find anything when I searched so the thing I got going for me it's that I can inspect the vehicle, but that's not that useful without your knowledge, so thanks for sharing.

I have no idea why @Kernal does it like that. His tips are always really good - I am pretty sure every one of us has benefited from one of his PMs at some point.

 

[inkpot]

Sounds almost like your timing/dizzy just slipped back 5-10 degrees. They actually run ok like that, but it makes them really doggy. Have seen this on several rigs.

 

[LandCruiserPhil]

Have you removed your tensioner? If so what type do you have, two were available for the 1FZ.

 

[ralphy1997]

I thought the tensioner had its own spring & not dependent on oil pressure. . .

 

[LandCruisinMy93]

Sounds almost like your timing/dizzy just slipped back 5-10 degrees. They actually run ok like that, but it makes them really doggy. Have seen this on several rigs.

Funny you should mention this as a possible cause as I am a victim of this very thing. I had set everything after a new timing chain and tensioner and chain guides and headgasket etc...etc... Then I drove it around and like a whole new rig for months. Then I went wheeling and was really stickin it to the fat pig and abusing the skinny pedal and viola! It started idling low and acting crappy and running like a hobbled fat sow. I popped the hood and went to advance the timing like the redneck I sometimes am, thinking maybe I could get a little more life out of her and low and behold the dizzy had bottomed to one side when it started centered the bolt was still tight and there was a slide mark on the dizzy body from the washer on the bolt that holds it. So...this does happen on occasion. @2slo has an advantage over me since the 97 has the OBDII and you should be able to plug in a scanner and read the timing directly and precisely without looking at the crank pulley.

 

[excessive]

Not saying its impossible, but i seriously doubt the timing chain jumped. there just isn't enough room or slack in the chain.

 

[2slo]

All helpful suggestions. The people on this forum are incredible! I won't really know until we tear it apart what happened. The guy I was going to do it with's dad just had a stroke so he's got to sort that out. Hopefully the VA can do something. I don't have time or a place (nevermind the knowledge) to do it myself. Plan is to do it three weeks from now. We were going to start tomorrow. Life...

The last thing I can ask is: "what else should I replace while I'm going after the timing chain?" Obviously head gasket since the head comes off, I'll do a search on preferred gaskets. Thanks!

 

[inkpot]

Did you ever just put a timing light on it to see how far you are off? It would be a real shame to tear it all apart just to find out that all you had to do was reset the ignition timing, not the cam timing. I have stood my rig ip on its tail a lot of time X but I never had a shortage of oil pressure!

 

[inkpot]

I have seen the timing drift quite a bit on two different rigs, both of which the dizzy lock down bolt was quite tight. No reason we could figure out, but it did it. Both of our rigs get wheeled hard and often. It doesn't take much time n effort to throw on a timing light and chech it out?

 

[Mighty690]

I thought the tensioner had its own spring & not dependent on oil pressure. . .

There are two generations. My '93s had the original OEM spring type, but when rebuilt the OEM hydraulic tensioners were installed. Just did what Cruiser Dan suggested. I don't even know if the OEM spring type is available, because Beno also sent me the hydraulic one for this latest engine.

 

[OGBeno]

There are two generations. My '93s had the original OEM spring type, but when rebuilt the OEM hydraulic tensioners were installed. Just did what Cruiser Dan suggested. I don't even know if the OEM spring type is available, because Beno also sent me the hydraulic one for this latest engine.

It is not available; the spring style supersedes to the hydraulic iteration.