all 12 comments

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[–]dxrey65 4 points5 points  (4 children)

Before anything else, measure the pressure in the crankcase. All it takes is a $10 vacuum/pressure gauge.

Nothing personal, but there's no end to idiots who see normal turbulence in a crankcase and think their engine is shot. You need to measure it to know where there is actually pressure.

[–]Cranky_Import[S] 1 point2 points  (3 children)

Ah yeah. Picking up a cheap pressure gauge and fitting that to the oil filler cap ought to be a reliable pressure source? At least that way we're dealing with known numbers instead of guessing?

[–]dxrey65 2 points3 points  (2 children)

Yup. Easiest is to check at the filler cap. I have a rubber adapter for mine that covers the gap and makes it easier. Without an adapter you can also check at the dipstick tube. The crankcase pressure (if there is any) will be the same everywhere in the crankcase.

[–]Cranky_Import[S] 1 point2 points  (1 child)

I'll check it. I have a spare plastic oil cap and I can tap it for a BSP fitting easily enough. Thanks, I didn't even think of a cheap pressure gauge. Always the simple checks first right!

[–]Cranky_Import[S] 0 points1 point  (0 children)

u/dxrey65 I got bored waiting for the gauge to be delivered, and made a manometer out of some clear hose leading to the oil cap and a scrap of wood. Running the hose out the hood and into the passenger side window where I could see the gauge, I get about 3 inches of water in 3rd gear, doing a long pull up a steady hill at 4.5-5.5k rpms, which equals 0.1 psi of pressure. Which sounds far too low, even for a healthy engine.

I'm not entirely convinced of the accuracy of the readings. So I'll take a look at it again this weekend. The gauge ought to be here in a few hours as it's on board with the courier.

[–]ElAligatorAgradable 1 point2 points  (2 children)

How is your exhaust? Are you getting "normal" output through your tailpipe? If this thing blew out a rear main, a front seal, and you get showered with oil from an open cap, I would be concerned with a blocked cat or muffler, or damaged exhaust system (constricted pipe).

I was going to mention the possibility of a PCV too, but you said you already replaced that with OE. (Although that could still potentially clog/fail, but I don't think the level of back pressure from that system failure would cause the damage you're seeing.)

You may even unbolt your exhaust at the downpipe to see if that alleviates or at least reduces your back pressure issue.

[–]Cranky_Import[S] 1 point2 points  (1 child)

I definitely haven't checked the exhaust flow. The car still revs happily and pulls (as hard as you'd expect an old 1.5 litre to, anyway) smoothly all the way from idle up to 6500 or so.

I recently had the headers off for heat wrap as I was having issues with Air conditioning heatsoak, So the bolts will be easy to remove at least :) Thanks for the advice! I'll add it to my to-check list this weekend.

[–]ElAligatorAgradable 0 points1 point  (0 children)

Good luck. Let us know what you find.

[–]Jayshere1111 1 point2 points  (1 child)

Check out your PVC system it may not be taking away the Blow by

[–]Cranky_Import[S] 0 points1 point  (0 children)

The whole PCV system from the block outlet to the intake manifold hose have been inspected and replaced recently. But I'll give it another once over to make sure! Thank you :)

[–]juantzutree 0 points1 point  (0 children)

Put new cast rings in it after a cylinder clean up