In the process of swapping a 3.4 into my '90. Did compression test before pulling the engine and leak down test after, and 5 cylinders held between 78%-92% pressure. Cylinder #3 had lower compression and only held 64%. mostly leaking from exhaust valves, so I decided to pull the heads while the engine was out on the stand, and get them resurfaced. Cheaped out and went to a new machine shop to save $50 and 15 mins driving, thinking it should be a run-of-the-mill job that anyone could handle. Got them back Friday PM, put RH head on its side and naptha over the exhaust valves - they were still leaking, although it seemed a little slower the same test before rebuild. Set heads on the block and checked valve lash, 6 of 24 clearances out of spec, so had to deal with that too.
Finally got them bolted on late yesterday and did another leakdown test. Cylinder #1 held 86% pressure before valve job, it now holds 52% (edit: mostly leaking from intake valves). Cyl #2 used to hold 83%, now holds 50% (leaking more from exhaust valves it seems). Cyl #3 did go up, from 64% to 70%. I stopped there because one intake valve on #4 has zero clearance from swapping shims to fix their lash FU, and because I'd seen enough. So after banging my head on the wall for a few hours I went to bed, confirmed the numbers again this AM, and now I'm here. Will pull the cams and check the rest of the cylinders later.
Has anyone seen this before? Without removing valves to measure yet, is it possible they cut the angles wrong and the valves can be saved by a competent shop, or more likely that they removed too much material and I have to buy all new valves? I see in the FSM they spec a minimum valves length, which would imply that there's also a maximum allowable amount of material that can be removed from the seats, yes? What would you do? I'm torn between trying another shop or starting fresh with reman heads from Ebay, especially if I have to buy all new valves. Looks like I'm out the $100 for another set of head gaskets either way, say nothing of hours and hours more labor.
Finally got them bolted on late yesterday and did another leakdown test. Cylinder #1 held 86% pressure before valve job, it now holds 52% (edit: mostly leaking from intake valves). Cyl #2 used to hold 83%, now holds 50% (leaking more from exhaust valves it seems). Cyl #3 did go up, from 64% to 70%. I stopped there because one intake valve on #4 has zero clearance from swapping shims to fix their lash FU, and because I'd seen enough. So after banging my head on the wall for a few hours I went to bed, confirmed the numbers again this AM, and now I'm here. Will pull the cams and check the rest of the cylinders later.
Has anyone seen this before? Without removing valves to measure yet, is it possible they cut the angles wrong and the valves can be saved by a competent shop, or more likely that they removed too much material and I have to buy all new valves? I see in the FSM they spec a minimum valves length, which would imply that there's also a maximum allowable amount of material that can be removed from the seats, yes? What would you do? I'm torn between trying another shop or starting fresh with reman heads from Ebay, especially if I have to buy all new valves. Looks like I'm out the $100 for another set of head gaskets either way, say nothing of hours and hours more labor.
