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View Full Version : Rings or valve guides?



w261w261
10-08-2006, 04:22 PM
Here's the scenario: car starts and runs from cold with no smoke. But, after taking it up in a lower gear (auto tranny), then letting it run down holding that gear (e.g. the engine is not free-wheeling), upon a quick stab of throttle there's a pretty good puff of blue smoke, then nothing. Is there a way from this to tell if the valve guides are worn, or the rings? Thx.

88Accord-DX
10-08-2006, 07:57 PM
There are couple ways to see if the rings are shot. Do a compression test on the cylinders. Write them numbers down, then squirt about 2-3 tablespoons of oil in the one being tested. If your compression raises, more than likely your rings are worn. That is called a leak down test.

Another way is to use a cylinder leakage tester. It preforms the about the same as a compression gauge. You plug it into spark plug hole with that cylinder at TDC. You then blow compressed air into it, if leakage is severe enough, you may hear air blow out the intake manifold (bad intake valve),exhaust system (burned exhaust valve), or breather (bad rings, piston, or scored cylinders).

The valve guide wear can only be done with the head off the engine. It is measured with a dial indicator, also can me measured with an outside micrometer measuring the valve. Then using a small bore gauge to meausure valve guide journals. Subtract the measurements, gives you valve guide wear.

lostforawhile
10-10-2006, 08:20 PM
there is also the possibility that it's just valve stem seals. I know mine had completly distintegrated. these can be replaced on the car with a special adaptor for an air hose. it screws into the spark plug hole. if your valve guides themselves are worn,they can be knurled during machine work on the head this raises a cross hatch pattern inside of the valve guide and also provides excellent oil control . actually replacing the valve guides on this cyl. head is a very involved process that involves special tool to set them to the correct height then reaming to the proper diameter. also the guides are supposed to be frozen before installation because they are an interferance fit. knurling the guides brings them back to proper spec without having to replace them. it's prety easy to get oil into your cyls. with bad seals due to this being an overhead cam engine. theres a lot of oil sitting over the cylnders and more ways for it to get there. one more possibility to check,have you overfilled your oil at all? the way the pcv system works on these cars, there is a vapor, liquid oil seperator on the back of the block that is under vaccume to the oil pan. air is supposed to go from the air cleaner through the breather,circulate though the engine,and be picked up at the pan,travel through the seperator to send liquid oil back to the pan,then be pulled up through the pcv valve,and into the intake. it's really easy to overload with a little too much oil in the pan,and sometimes it can suck oil through the system to the pcv valve. it doesn't take but a little to create a big puff of smoke.

88Accord-DX
10-10-2006, 08:35 PM
The thing with replacing the valve stem seals, is you need to keep the valve from falling down in the cylinder. (without pulling the head) Either blow compressed air in the spark plug hole or turn that particular cylinder on TDC before removing the retainer & spring. I agree that valve stem seals can cause a puff of smoke, but generally you see it from a cold start up.

It is cheaper to knurl the valve guides to restore tolerances. Though the valve guides should be taken to a machine shop to drive them out & install new ones & to knurl them. Would need to pull the head off though.

88Accord-DX
10-11-2006, 07:16 PM
Just want to add a little something to this thread. When your replacing the valve stem seals, you'll need a valve spring compressor to remove the spring. Also, when you have the head off, remove all carbon deposites off the valve & around the seat. Pour water on the valves while the head is up-sdide down. Make sure the water doesn't leak past the valve with the head upside down. Either lap the valves or recondition the seat for proper seating.