high mileage motor. done at 4000 rpm

[buickruss]

Not the car in my sig. This one is mostly stock. 140,0000 miles. starts and runs well up to about 3800 rpm. then noses over like weak valvesprings. Thats one of the first things Ill look at next week, but I would expect it to rev higher than this. I attached a powerlogger file if anybody wants to give any other advise. nothing looks too bad to me.

No codes. Stock except for
TT chip with 60# injectors. 3" MAF with translator. TR6, new exhaust with test pipe.

 

[TTA308]

My guess would be valve springs, camshaft, timing chain all wore out.

 

[SCOOBY DOO]

You're not quite full throttle...but the RPM's are 3300. It'll need valve springs and a timing chain. Also a fuel pump and Denso 02 sensor if you don't know how old either are. Go with 981's.

 

[mblum]

I agree with both gents thst have responded. My 90k mile engine wouldn't rev past 4k when I acquired the car. Both my timing chain and valve springs were shot. After replacing those items and some other general maintenance items it pulls easily to 5300, probably higher just havnt taken it there yet.

 

[buickruss]

oil Pan was very clean when I did the rear seal, so I think timing chain was already done. I’ll be shopping for valve springs this week

 

[TireFryer]

Might be worth confirming the chain was done. I thought mine had been.. nope.. stock, nylon teeth were cracked and I found pieces of it in the pickup. I’d confirm it. Otherwise valves marry pistons.

 

[mblum]

If the timing chain is unknown its best to check it. Mine was replaced at some point as the stock one was not in there when I opened it up. I did however find the timing set they used must have been a cheapie, had about .375 of slop once the tensioner was removed. Not good. New one from TA performance was a perfect fit.

 

[~JM~]

135K miles:

 

[buickruss]

New valve springs in. Originals could be compressed by hand.....Same symptoms. Runs smooth up to about 3500 rpm. In park can rev higher. Im assuming Ill do the timing chain next. Will check with TA .
Since Ill have some time, Is there a way to diagnose it without removing the timing cover?

 

[1KWIKSIX]

It it’s the original timing chain & gears at 140,000 mi.
No need to check .
Change em both out + the valve springs for comp cam 980 or 981’s.

 

[Chuck Leeper]

A bore scope thru the fuel pump flange?

 

[buickruss]

ive been looking for an excuse to buy one of those.

 

[Mr.Spool]

Compression test and leak down.
And everything said above

 

[Chuck Leeper]

ive been looking for an excuse to buy one of those.

We use ours frequently for a "looksee" in, around, under, various places. Sure beats becoming a contortionist to get into tight places. Especially, at dinosaur age!

 

[Anthony P]

A bore scope thru the fuel pump flange?

Glad you said it Chuck...part of the "work smarter, not harder" approach.

the driver side chain slop shown in the video above, in post #8, should not be there. any slop would clearly been seen through the fuel pump block off plate as Chuck said.