[reweb67]

I have 2 cylinders (#1 and #3) that have been getting a lot of oil dumped in them. This fouls out 2 of the plugs in about 5 miles of driving. The other cylinders do not foul out. I have checked for signs of a bad head gasket and see none.

This is a 1967 mustang with a stock 200 six. Compression is 180 to 190 on all cylinders. I just did a full tune up and rebuilt the carburetor. The problem is definitely oil related. I can see oil in the cylinders if I look in there with a flash light. The other cylinders are dry. Crazy part is the car does not smoke at all that I can tell. Do not know how to explain that!

Car has roughly 25 to 30,000 miles on a rebuild that was done quite a while ago (15 years). The car is a my weekend fun cruiser so does not get a ton of miles each year.

Hoped I would find bad valve seals but they look fine. Maybe a bit less flexible than new but they do remain pretty flexible and have no rips or missing pieces.

Using the rope trick I pulled the valve spring of off my #1 intake valve (plug fouls out on #1). The valve is tight up to the head and being held up by the rope. I can rock it back and forth pretty good. Not a ton but enough to hear a tick tick sound as it hits the sides. How much is to much? I don't mind pulling the head and having new guides put in if that is what it takes to fix it. Obviously don't want to do that if some rocking of valve stem in the guide is normal. Should it move back and forth at all?

I would like to post a video of it rocking to get opinions on if it is bad or not. I plan to take a video with my iPhone. How do I go about posting a video? I am familiar with posting pictures and can do that no problem.

Thanks much for any advice / help!

 

[reweb67]

Here is a picture. Probably no need for a video. You can see the guide is out of round. I can wiggle it and move the stem into the part that is out of round.

Guessing the guide is toast? If the valve seals are good would this be enough of a problem to foul out a plug with oil in 5 miles of driving?

 

[2nd 66]

quite possibly

 

[reweb67]

Here is another picture.

 

[69DroptopGT]

I would say there would be minimal rocking as the guide is not a short contact point. And I know it is just a picture but it almost looks like they may be bad.

 

[reweb67]

For comparison here is a pic I borrowed from a thread on VMF about replacing valve stem seals. That I'm guessing is what a healthy guide should look like? Nice and snug. Mine clearly does not look like that. Don't want to pull the head though if this is not my problem. Can anyone say for sure? Thanks!

 

[zray]

The proper way to check is to open the valve by the amount it will be opening via the camshaft. A 1/2" is a good estimate. So in your case with the head still in the car, push the valve down against the rope about 1/2", then rock it back and forth. More than 0.001" is showing wear. I'm guessing you have a lot more than that.

You mention the oiling is worse on #'s 1 and 3. Therefore I'd suggest checking the wear on a good cylinder for comparison.

Also mentioned is the fact the plugs on 1 and 3 are completely founding out in 5 miles. This tells me you have worse problems than just worn out valve guides. You either have broken oil control rings(s) or egg shaped cylinder(s) or a combination of valve guide wear plus the other issues.. in any case I don't see how you are going to avoid taking off the cylinder head at a minimum, and most likely, an engine removal.

Best of luck with the repairs,

Z

 

[awhtx]

The Ford shop manual says intake valve stem to guide clearance of .0008"-.0025" with a wear limit of .0045". That's tight enough that you won't feel the valve rocking in the guide. I say your head needs to come off and guides installed. May as well do all of them.

 

[Paul1958]

Car has roughly 25 to 30,000 miles on a rebuild that was done quite a while ago (15 years).

When an engine is rebuilt typically one of three things is done if the valve guide-to-valve stem clearance is excessive:
1. The valve guides are replaced. Sometimes the valves are replaced as well. $$$
2. The valve guides are reamed oversized and valves with oversized stems are installed. $$ - $$$
3. The valve guides are knurled which reduces their inside diameter (to reduce clearance) but significantly reduces the internal surface area of the guides - leading to rapid wear. $
4. Another option is to obtain a remanufactured cylinder head that has had one of the three options already done to it.

Do you have records of what was done during the rebuild? Perhaps the valve guides we not even addressed at that time.

Paul

 

[69DroptopGT]

25-30k miles on an engine that is not fired up all the time can lead to guides dying. 5 miles to foul is a lot of wear though. It is definitely fouling with oil correct? Usually you will have the puff of smoke at startup with bad guides but not always. If rings, you probably will see some blow-by but not always. I would lean towards the bad guides as the pic kinda looks like some wear and the slop that you describe. With that type of ware you may be get valve job and I would probably replace the valves. Or if you had another head you could get affordable you may want to try that. With the type of wear that has I would expect issues with valves and seats and would get them inspected if not replaced. Price of valves is 80-170 depending on what you want. A good machine shop will inspect them for you at a reasonable but they are getting harder to find. Then all the machining and ect. The take of all of this is, do valves first before you think pistons and ect.

 

[zray]

OP, your machine shop should be able to install valve guide liners, a process that my favorite cylinder head shop does:

Services | Brooks Elliott


Z

 

[reweb67]

Thanks for all of the replies.

I spun the engine by hand and lowered the rope down so the the valve would drop a 1/2 inch as suggested. Wiggling is worse like that. Has a nice solid clunk clunk noise as the valve stem hits either side of the guide walls. That can't be right!

15 years ago I pulled the engine myself and took it to a local speed shop (now out of business) to be rebuilt. I asked them to do a full rebuild and told them to put in valves suitable for unleaded fuel and to port / polish the head. I was not doing the rebuild on the cheap. They offered to install an rv cam and I said yes. Did not know enough then to ask specifically about the guides. Guessing they were probably knurled or possibly left alone as the engine was pretty low milage when rebuilt. The car was built in San Jose CA and was still in San Jose when I bought it. The car had sat for over 15 years when I got it in late 2000.

Regarding blow by, there is no blow by out of the oil fill cap or dipstick when removed if I have the PCV hooked up. If I remove the PCV there is some out of both but it looks more like steam than anything else. Possible just a bit white looking too.

I did think maybe I had some stuck oil rings and I did the soak with marvel mystery oil for a couple days. This is were you pour a few ounces into each spark plug hole and let it soak for a couple days. Did not help or have any effect. Car did not smoke at all after that either!

Will look into valve guide liners, thanks.

Lastly, it is suggested -- 25-30k miles on an engine that is not fired up all the time can lead to guides dying.

How would that work? Not enough oil?

 

[69DroptopGT]

If it goes months without running oil drains out so you have a dry start. Not usually a problem but it can be. Kinda why re-builders put the assembly lube in when rebuilding. Assembly lube stays in place for longer periods of time and many people get their engines rebuilt way before they are ready to fire them up. Additionally, if there is any contaminates in the oil they will hang up in places like this. l Some people actually take their coil wire off and turn over some before their start it up to prime the oil throughout the engine if it has not been started in a while.

 

[Paul1958]

Can you tell if the guides were replaced - they would be separate pieces from the parent head material. Ill bet the guides were either not done at all or just knurled which is really a short term 'el cheapo' fix. Either have you guides replaced/resized or get a reman head that has replaced/resized guides.

Good luck
Paul

 

[awhtx]

You can buy replacement valve guides in either cast iron or manganese bronze.

https://www.precisionengineparts.com/products?lightbox=image1kyu