Actually after seeing your post about valve clearances, I felt 10x better this morning. Yesterday, I was all ready to book a trip to Mexico and my heart dropped when I saw the compression numbers. Even if I just have to take that cam out a few times, it'll be much better than tearing that whole head down again!
'93 Previa DX (162,XXX mi)
Checked my valve clearances today, but there's a still a little bit of a mystery here for me.
Spec says that it should between 0.15-0.25mm on the intake side and 0.25-0.35mm on the exhaust side. All of my intake clearances were in spec. All of my exhaust clearances were out of spec. Seems to make sense since I only did lapping on the exhaust side and none on the intake side. Also, I had used the old camshaft on the exhaust side.
Anyway, here's what I found on my exhaust side today (2 valves per cylinder):
Cylinder 1: 0.13mm...0.15mm
Cylinder 2: 0.23mm...0.21mm
Cylinder 3: 0.10mm...0.04mm <--- !!
Cylinder 4: 0.20mm...0.13mm
While all exhaust valves were out of spec, the weird thing for me comes in that my worst one is actually cylinder 3, not cylinder 4. But in my compression test, I had I had 160psi compression in cylinder 3, while I only had 70psi in cylinder 4. Because cylinders 1 and 2 (both about 155psi) and 3 were all out-of-spec, but also still had decent compression, that leads me to believe something else might still be wrong with 4. I do remember doing a water test on all the cylinders after lapping to test for leakage, so for some reason I think the valve seats should be okay? I am actually not sure on this one. Any ideas
'93 Previa DX (162,XXX mi)
perform a leak down test to determine where it's leaking
Well, my theory's blown. If you have any clearance at all, then the valves are closing. Fine-tuning the clearances won't fix your compression issue.
I think TheMAN's suggestion is a good one at this point. If the valves are sealing, you are either leaking at the head gasket or past the rings.
Found my leak today. It's the piston rings. I had a ton of air coming out of the oil filler cap and oil dipstick hole. A tiny bit of air, but noticeable, was also coming out of the throttle body too.
I had done a leakdown at the outset of all this, but guess I did it wrong originally. Now it looks like I'll be needing to work on the bottom half of the engine too.
'93 Previa DX (162,XXX mi)
Hello all
Reviving a rather old thread as I prepare to replace a blown HG on my '94 N/A egg. I plan to take Samay's approach and do the work w the motor mostly still in place.
I've been looking through related posts here for more info on what to replace while I'm doing this work but haven't landed on a succinct list. So far I am thinking h20 pump, t'stat, and any other hoses that I can access. I wish I could do the timing set but I don't think I'll be able to remove the whole engine and trans. I'll need to replace one plug as cyl 1 is the culprit per a pressure test, and I have ordered a new prepped head in case the old one is cracked. My motor has over 150K on it, though it's the second engine in this van which is showing 309 on the odo.
Are there any preferred vendors for these parts? I've read that the OEM HG is the 'only way to go' so I won't skimp on that. What about water pump and other parts?
Originally Posted by maestro123
Figured I might as well create a thread for all my blown head gasket stuff. Gonna try to keep the forum nice and tidy
Here were some of my previous threads that were related:
http://www.toyotavantech.com/forum/s...hite-and-brown
http://www.toyotavantech.com/forum/s...shaft-bolt-off
http://www.toyotavantech.com/forum/s...oil-pan-gasket
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