I think you have found the problem and fixed it.  If the guides are worn out, you would be able to wobble the valve around with your hand while the head is off. You would also get a low vacuum reading if the intake guides are really bad.

Thanks John,

I haven?t needed to adjust valves yet so I assumed the 175 was similar to my 218 & 230 engines.   That being the case I can then understand how the valves could be changed and still have leaky valve guides.

PS? A big ?At-a-Boy? to Then & Now Automotive for re-vulcanizing my front motor mount and getting it back to me in a week?s time.  Priced right at $37.50.

Chet?

Regarding the valve guides, these engines had the guides bored into the block, i.e., they did not use valve guide inserts.  However, if they are worn beyond specs, valve guide inserts can be added.  A local machine shop put in brass valve guide inserts in my 29 a few years ago for a very reasonable price.  If worn valve guides are a problem, it should be an easy fix for a good machine shop.

Quote from: Buddy Romines on May 28, 2008, 09:11:02 AM
... I think I would suspect the rings or intake valve shaft wear.

I am thinking piston or ring mismatch.? The top of my pistons is stamped X183.??? Whatever that means.? ?The diameter of the stock cylinder wall for the 175.5 engine is 3 x 5/8? or 3.625.? I measured the inside diameter of the bore at 3.645 with no taper top to bottom all cylinders.? ?It appears the engine was bored out 0.020.? This is actually good news, if need be I could go another 10 or 20 thousands down the road apiece.

I don?t have the time right now to pull a piston and investigate further.? I will put it all back together and see if the oil consumption problem subsides with the pressure relief valve working properly.? If not.., I will suspect some type of mismatch between the bore, pistons, and rings.? The picture is very dark but the valves and cylinder walls all look real good.? I agree with your diagnosis that poor valve guides would be a problem but I can?t see someone going to the trouble of replace the valves and not replacing the guides.? I could see someone putting in over sized pistons with the wrong ring set.

The valves are Thompson.? ?If anybody knows anything about the X183 stamp on the pistons I would greatly appreciate any and all input.

Tks, Chet?

You mentioned that there was oil puddled on top of the pistons.? I'm not sure how the oil presure would do this.? I feel the only way to get oil into the combustion chamber is beside the intake valve shaft or around the piston rings.? I think I would suspect the rings or intake valve shaft wear.

The picture indicates the problem may be the valves since they are very dark, this may indicate carbon buildup on the valve surface.

Sounds like to me you are right on top of the problem. A pressure relief valve that will not relieve is bad news and could even cause a crack in an oil passageway. Good troubleshooting! Paint the head, put her back together and drive it.

Jim

I have been having a lot of trouble with burning an excessive amount of oil.? When at idle the oil pressure reads just under 40 psi and when driving my gauge is maxed out.? The motor runs strong and was rebuilt not too many miles ago by the car?s former owners.? Anyway since I was draining the coolant to replace the radiator with an original one I decided to remove the head.? My two purposes are one to inspect the pistons & cylinder walls, and the other reason is to repaint the head silver.?

With the head removed I found pristine cylinder walls with hardly noticeable edge ring.? The cylinders had oil puddled in the cylinders with a lot of black carbon on the pistons.? I cleaned up the area and decided to trouble shoot the oil pressure.



Thinking that my car?s gauge was inaccurate I installed a new modern oil gauge and cranked the engine with the starter.? The gauge read 38 psi after about a half a minute of cranking.? This is the same value as my interior gauge so I guess my old gauge is correct.?

I then decided to remove the pressure relief valve assembly.? ?After inspection I could not push the valve in far enough to allow the port to open.? I disassembled the valve and cleaned the spring, plunger, and cylinder.? ?After reassembling the parts I could now push the plunger in to allow the valve to open.? ?I think this was my problem.? I reassembled the valve into the engine and set the pressure one turn from minimum pressure.? I cranked the engine with the starter and the pressure pumped up to 20 psi and with continued cranking would go up to 35 psi.? ?The pressure looks much better now then when I started.?

Once I get the motor back together I will adjust for 35 - 40 psi maximum when driving at a normal speed.? I think this should help the excess oil burning problem by allowing less oil to blow by the cylinder rings.?

What do you guys think.?? Is there anything else I should do while the head is off.?

Chet?