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Thread: O.T.- valve guide repair
03-17-2006, 06:25 AM #1
I posted a topic about my Ford Probe smoking on start up after changing valve seals. I found out which cylinder was doing it and removed springs to find exhaust valve was loose in guide. My question is how do you go about changing the guide? Are they just pressed in? I see a picture of them on Auto zones web site and they are only about $10. I will replace the valve too, but I don't want to dump a lot of money in it as it is just a beater I drive to work. Do I need any special tools?
03-17-2006, 07:01 AM #2
I assume your going to have the head off ?? I would talk to the engine shop about it first, you might find their price is cheap, even if you don't jawing with them you might learn a bit about how they do it on that engine. There also might be an oversized valve avail from Ford, then you'd just ream the guide to fit, once again the engine shop MIGHT surprise you on price, I have seen some stuff like that be pretty cheap if it is just a 30 minute job for them.
03-17-2006, 10:45 AM #3
Not familiar with the Probe engine and whether it has iron head or aluminum.
Most heads that are cast iron built today have integral guides and require special machining to cut out the old before pressing in a new one.
Aluminum heads will have pressed in iron gudes, most likely.
You need to ask around among auto people you know and trust for a referral to a good automotive machine shop to do this job right.
Their machines are job specific and they can pop another guide in there before you can set up , much less cut the guide out, regrind seat, etc.
Plus if you have the head off, you are gonna want to do a full valve job anyhow.
If you aren't losing too much oil and only smoke a bit on startup, you may be trying to make a silk purse out of a sow's ear! Could be more practical to just ignore the smoke.
03-17-2006, 11:07 AM #4
We drive them out with some kind of a modified punch. Has a small pilot that goes inside the valve guide, and a shaft on the outside of it slightly smaller than the valve guide diameter. The other end fits into an air hammer gun. Takes about 5 seconds if you have the right tool.
If I were you, I'd sure like to get my hands on some specs to see if the new valve guide you put in will be loose in the bore. If I didn't have specs, I would most likely want to go to an oversize valve so I would know that my bore and my valve guide would have the correct press fit. I'd also check and see if the ID of the valve guide will need reaming to size after it has been installed. Good luck.
03-17-2006, 11:14 AM #5
Welcome to my life!
the guides ar indeed pressed in, usually driven in an out with driver mounted in an air hammer, although it can be done manually with a hammer. The drawback is someties the hammer methods breaks the guide.(you willneed some sort of piloted driver) After the guides are replaced you WILL need to grind the seats as they will not be concentric with the new guide. Make sure, if you attempt this yourself, that you position the guides the same as the old ones, if too high the retainers will hit the seals, if too low, you might run into the radius under the valve head and not allow it to close fully. In my shop, a complete rebuild on this head would be in the range of 250 -300 bucks, dis-assembly, cleaning, check for cracks, replace guides, grind valves and seats, setting the stem height,checking the springs,setting the installed height of the springs new seals, resurfacing and reassembly. Unless you have the equipment,your in for a lot of work. If you are really lucky, you MIGHT get away just lapping the valves after the guide replacement, but that doesnt happen very often.
If you need any more advice, let me know. Been there 1000's of time in the last 15 years!
03-17-2006, 11:17 AM #6
BTW, reaming the guide for an oversize valve, as mentioned above, is a fairly common process, but has one disadvantage, your valve stem seals are not made for and oversize stem, and will wear prematurely from being over-stretched,a year from now = more smoke from wore out seals,again
PS_edit- if you want pics of a guide driver or need any specs for the head, tell me exactly the year,CID ect and I can get em too ya easy enough
03-17-2006, 01:14 PM #7
Holy COW, I really like the guy over in Archbold oHIo then if he does a complete hot tank, new cam bearings, bore and hone, goes thru the heads, re-sizes rods and including the new pistons out the door with all the seals, rings, and bearings for 850.00 and you put it all back together. This for a small block chev. 350 boring .03 over. (Brother in law just had one done)
03-17-2006, 01:59 PM #8
I just had a valve job done for a honda 4 cylinder. Went to the local machine shop, $165 parts and labor +$80 for a head gasket set (everything head gasket and up). He replaced 2 valves (burned ex. valves) and 4 guides, resurfaced the head, cleaned it, re assembled it. Turned it around in 4 days. I was very happy. I could have done it myself, but for me, I get valve jobs and heads done once every 10 years give or take, so I leave it to people who do this everyday. Time is money, and for the price I paid, I'd do it that way in the future.
Back to topic:
Pressing in new guides, usually they have a special drift that limits how far you drive them in. It looks like a punch with an outer cylinder that looks like a deep socket. You drive it in until the cylinder bottoms on the head. Then you know the guide is seated properly. The pros may have a universal type tool, that allows you to set the depth for different applications. I don't believe you can fix this without pulling the head (if you already haven't).
03-17-2006, 02:11 PM #9
Oh, I'll add, I don't believe you can fix this properly without removing the head. Key word is properly. You might be able to "hack it" if you don't want to spend the time and money doing it right, but my experience has been, the stingy man pays twice. (don't take that as a slight, I'm not implying that you are stingy) Of course, these days I'm starting to develop the philosophy of a boat captain, and pretending that I'm out to sea, and doing whatever it takes to get back to port. If I was "out to sea" so to speak, I'd look to see if I could put the guide in with some non-hardening sealant, and put a new seal on top, if it is an intake valve. But I can't recommend this to anyone, and keep in mind, it is just to get "back to port". An oversized guide should be reamed to fit, and you cannot do this without pulling the valve (and therefore, the head).
03-17-2006, 03:34 PM #10
I have seen a lot of cracked valve guide bosses caused by air hammering or hydraulic pressing guides in and out of aluminum heads. Especially heads that have been ported and have had their valve guide bosses streamlined.
I have three heads sitting on my workbench right now that I bought on ebay, which seems to be the way folks dump stuff like this. Of course they don't mention the problem in the listing...
The way to avoid cracking the bosses is to pull the guides not press or hammer them out.
I tap them and use a puller, there is a lot better control, and that way you are applying the force where the head is strongest. Then when reinserting the new guides, I heat the head to 300 degrees and press the guides in with a bit of anti-seize. I have never had a head crack doing it that way, and I have been rebuilding heads for 30+ years.
03-17-2006, 04:10 PM #11Oh, I'll add, I don't believe you can fix this properly without removing the head. Key word is properly.
03-17-2006, 07:28 PM #12Holy COW, I really like the guy over in
03-17-2006, 07:46 PM #13
I will take the head off this weekend and evaluate. If I indicate the valve stem side play, How much is too much?
03-17-2006, 08:24 PM #14
whats a bit of smoke? It keeps the exhaust from rusting, I reckon....
You say its a beater - as long as the plugs aren't oiling up, keep driving it! My free advise [img]smile.gif[/img]
If its aluminium head, wouldn't they have to heat the head to remove the guides? Otherwise they will remove material as you remove them?
Course, you'll have to do all the guides, and may find the stems have worn...also need to re-cut seats after this operation.
03-17-2006, 10:01 PM #15
Yeah, I'll agree the some of the others here. If you haven't pulled the head, and you don't have to pass a smog test, I'd leave it. You say it is a beater, if it just smokes on startup, and doesn't consume more that 1 quart every 3000 miles, I'd leave it alone.
Disregard the bit I said about the sealant, I misread your post and thought you said the guide was loose.
Also, a question for the others: if the seals on the exhaust valves where trashed, wouldn't it just smoke on startup, as the exhaust doesn't have any manifold vacuum to suck oil in like intake valves would? If your intake valve seals are trashed, it will suck oil in, due to manifold vacuum.
How many miles does this car have? Stick or automatic? Fuel injection or carb? Throttle body or multipoint? I ask these as a evaluation criteria. If it is a automatic with high mileage, I wouldn't put much work into it. If it has multipoint fuel injection, I'd hesitate to pull the head, because of all the lines and wires that need to be marked. Carb or throttle body, not as big a deal.
Things to consider. Of course, as peter said, it is free advise.
03-17-2006, 10:12 PM #16
Engine Builder, he has been around a long time, but he has a commercial building, all of that stuff. I could never put $300.00 into a cylinder head. I'd buy a new crate motor before I'd do that. (ya it costs more, but you get lots more too).
Everybody has to eat I understand that.
03-18-2006, 01:27 AM #17
Honda & Mistubusi recomend heating the heads
to 400 deg F, before pressing out guides &
also before installing the new guides.
You will also have to recut the seats &
lap in the new valves..Check Spring hight
and shim if necessary. you will also have
to Ream the new guides before cutting the
I agree with enginbuilder, parts and labour
on a complete head job, $300 to $400. Most
remanufacturers will charge just to give
you an estimate. Any amount less is;
"a job not done ".
03-18-2006, 03:03 AM #18
What bothers me is that in your posting on oil burning you wrote"... it only does it one out of four times ..." Seems like if it was doing it infrequently like you state, it would be something other than valve guides. Back in the day, I had a couple of Ford 200 CID 6-cylinder engines with bad valve guide seals and the big tip off was that the plugs would carbon up towards the side of the intake valves.
03-18-2006, 04:35 AM #19
Picked this up from my Father " Line Chief of the Burma Bridge Busters B25 bomb squadren"
Never drive a used valve guide out of an aluminum cylinder head. You will drag carbon through the hole and damage the head.
Instead, machine or drill the top of the guide off, then counter bore the remainder of the guide to relieve the press fit. The guide will come out easily the direction it was pressed in, preserving the hole.
Then hone the hole true to bright metal, this will ensure maximum heat transfer from the guide to the head.
Mandrel turn an oversize guide for the proper press fit, heat the head and press in with proper tooling.
Here is a simple set up drilling out Harley valve guides on my old shop dog Monarch EE lathe.
Yes, It is spendy, but I have zero valve failures.
03-18-2006, 06:13 AM #20
I used to change the valve seals in 289's and 302's with cast iron heads. They didn't have separate valve guides, just a hole in the head. When I saw the engine smoking on startup, I figured it was time. I am sure there was probably wear in the guides but I just put new seals in. A friend of mine had a 351w in a van that had a funny noise in the exhaust. Months later we pulled the heads and found one exhaust valve with a large portion of it missing. He drove it for a long time with the missing piece.