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Stuck lifter? Valve problem? Any advice? (long) Posted by kenS [Email]  (#606) [Profile/Gallery]
(more from kenS) on Tue, 14 Feb 2023 19:53:28
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I *think* I’m having a problem with either a sticking lifter, valve, or maybe something worse? Car (1987 900T, 225k but reasonably well cared for) was running fine, then started stumbling, unstable idle, sounded like a diesel. I went thru the usual suspects (vacuum leaks, fuel & oil pressure, AMM, ignition, timing), all ok. Then I looked at the plugs, 1,2,3 were ok, #4 (furthest from firewall) was dark, like carbon fouled. And, when I unplugged injectors 1,2,3 the engine would almost stall, but unplugging #4 had no effect. I thought “bad injector?” and replaced it with a rebuilt one, didn’t help. The injector wiring is ok, it is getting the on/off voltage pulse. I went through old postings on this site, and came across the “stuck lifter/ cam follower” as a possible issue. So I removed the valve cover to check the oil spray bars. They were in place, but had popped loose towards the front of the car (over cylinders 3,4)--- not completely loose, but the o-rings were not fully seated. On reassembly, the engine sounded a bit better, but still not right. Let the car sit for 2 days. Today I did a full compression check, with the following results: #1 170(dry), 180(wet); #2 165(dry), 178(wet); #3 165(dry), 168(wet), and #4 150(dry), 160(wet). So I installed new plugs (old ones were BCP7ES, new ones were BCPR7ES), put everything back together, and started it up. It immediately sounded better, and once the O2 sensor started cycling it sounded normal, stable idle etc. Went for a test drive and the engine was back to normal, ok power, turbo boost ok, no stumbles.
So the question is, did I have a stuck lifter (from oil starvation because of the spray bars) and it took a while to free itself, or do I have something more serious going on with the #4 cylinder? Is the lower compression in #4 a sign of coming trouble? Are there other tests I can run, short of pulling off the head? Would a leak-down test be useful?
, Tue, 14 Feb 2023 19:53:28 <-- Viewing This Message
, Tue, 14 Feb 2023 22:26:39
, Wed, 15 Feb 2023 03:35:01, Wed, 15 Feb 2023 12:41:02
1, Wed, 15 Feb 2023 13:01:19
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