1989 3.6l, 300 k miles I am rebuilding the engine head. The car was consuming qt of oil per 300 mi, and woud foul a catalyst in 2 years, so I think valve guides should be replaced (piston rings replaced about 100 k mi ago, but I missed to do valve guides then). Due to a burned exhaust valve, the head is off and valves are out, so:
JDHT shows valve guides only on the inlet side, but I see them in both the inlet and the exhaust. Would anyone know if they are the same catalog #, C29390?
If the valve guides were never replaced before, would 2thou oversize, .504" be the right size to buy now?
Has anyone punched the valve guides out and punch-and-hammer driven new ones in, or should it be done on the press (and thus taken to a shop)?
Obviously there are valve guides on both inlet and exhaust sides and I believe they were to the same part number - they certainly are the same on the 3.2 and 4.0 litre engines with the exact same part numbers. You should be aware that they only fitted valve stem seals on the inlet side up until engine serial number E163523 after which the seals EBC3531 were fitted to both inlet and exhaust (24 off)
If you are burning a lot of oil, particularly the dreaded blue puff on start up, a set of exhaust valve seals will provide a temporary ‘fix’.
I do notice that the oversize guides (C29390 and C29391) are currently ‘NLA’ (not available) from Jaguar.
There is an extensive write-up in the JDHT CD-Rom JHM1153 covering replacement of the valve guides in a 3.2/4.0 litre engine and I am pretty certain the 3.6 procedure will be the same since the guides are identical.
The procedure involves hand reaming the head holes to size and drifting in the new oversize guide by hand using their ‘service tool’ 18G 1432.
Thanks Bryan. Yes I have the disc; for everybody’s reference, for 3.6 litre engine, that JDHT CD ROM is JHM1172. The article is under Service Manuals => Engine => p12-95. Unfortunately the text is short and says only:
Check the valve guide wear by inserting a new valve into the guide to be checked; lift it 3 mm (1/8 in) from its seat and rock it sideways. Movement of the valve across its seat must not exceed 0.5 mm (0.020 in). Should the movement exceed this tolerance, the valve guide must be replaced. This is achieved by using Service Tool 18G 1432 to drift out the old guide. Ensure that the relevant service guide is selected prior to fitting. Remove the old valve guide and ream the cylinder head to the relevant dimension. Coat guide with graphite grease, immerse the cylinder head in boiling water for 30 minutes and fit the guide to the cylinder head. NOTE: To fit the guide the interference should not be sufficient to cause the use of excessive force.
For the replacement valves they refer to the chart:
ID | Part # | Dimension A | To be reamed to | Application
plain | C29388 | 0.5020 to 0.5015 | - | production
1 groove | C29389 | 0.5040 to 0.5035 | - | production
2 grooves | C29390 | 0.5070 to 0.5065 | 0.5055 to 0.5048 | service
3 grooves | C29391 | 0.5120 to 0.5115 | 0.5105 to 0.5098 | service
Unfortunately I can’t find what Dimension A refers to, but I know the reamer size for C29390 guides, if I can find those. Finding the right reamer might be a problem…
The Service Tool 18G 1432 looks like a pin punch. I have a set and 3 mm one is the right one. 1/4" would probably do, too.
To start with, I think I’m gonna use the pin punch and hammer out one old guide (that’s what they mean by “drift out”, right?). The circlip should be on the camshaft side, so drifting out should be done from the cylinder top side, as shown in Fig 2 on p 12-95.
The service manual for the 3.2/4.0 litre engines displays the valve guide data slightly differently (although with the same guide diameters) but referring to your extract for the 3.6 litre, I believe that ‘Dimension A’ refers to the first set of numbers for each size which is the diameter of the valve guide and you ream the head to the dimension in the second column to achieve an interference fit somewhere between one half and 1.7 thou.
Perhaps someone who has done that job on an AJ6 engine (I haven’t) will confirm the interference fit requirements. I would think that one thou is sufficient.
Just if anybody is following… I received the oversize guides, and to my surprise, exhaust valves do fit through cice and tight, but the inlet valves do not, looks like for just one or two thou, hard to tell exactly. Anybody having more info on this?
Well, the head went to the machine shop last week, and they called the next day to say that now that old guides are pressed out the .504 guides I brought are 3 mil too big for the bore, so I either supply smaller ones, or they drill the bores for another hour of work at $75. The supplier said .502 is the only smaller option, and the machine shop confirmed those will be the right fit, so I’m returning .504 for .502, not just for the over-all lesser price, but because I prefer right fit over making things fit.
For the tight fitting inlet valves the shop guys say it’s normal for new guides, they asked to have the at least one inlet and one exhaust valve, and they’ll work the guides for valves to fit through right.
