| Author | Message | ||
     Mark Aldridge Frequent User Username: mark_aldridge Post Number: 71 Registered: 10-2008 |
After correcting the previous running problems with our Spirit, it has now developed an exhaust valve problem on one cylinder - zero compression and a compressed air leakdown test produces a blast of air from the exhaust,with the rocker shaft removed.Putting a straight edge accross the valve stem tops suggests that the valve may not be closing completely (approx 15thou difference in stem height). Head removal looks straight forward, but are they prone to sticking like Cloud 1 and Bentley Mk6 ? Also are there any precautions required.I have tackled an alloy head on a Jag XK 6cyl engine but never a V8. Any advice would be welcome. Mark | ||
| Michael Hicks Experienced User Username: bentleyman22 Post Number: 32 Registered: 12-2011 |
Easy but should do the both and the vales | ||
| Jan Forrest Grand Master Username: got_one Post Number: 327 Registered: 1-2008 |
I don't know if this model engine has wet liners although others would. If it is the case then head removal has to be done a little more carefully to ensure that the liners aren't moved even a fraction of an inch as that could disturb the top and/or bottom seals which might then need replacing. I would suggest 'rolling' the head off the block by splitting them at the outer edge first so the liners stay where they're supposed to be. Don't forget that even an alloy head, especially on a V8, can be surprisingly heavy so it's best to have some help at hand when lifting it off the block since you're working almost at full stretch. | ||
| Mark Aldridge Frequent User Username: mark_aldridge Post Number: 72 Registered: 10-2008 |
Thanks for the advice. Jan, the engine is wet linered exactly as a Shadow; indeed the unit is a Shadow2 engine to all intents. Mark | ||
| Mark Aldridge Frequent User Username: mark_aldridge Post Number: 73 Registered: 10-2008 |
Help ! We have got the head loose on all but one stud, which is seized virtually solid. Have soaked in WD40, penetrating oil ,etc with no success. Have left it "hanging "on the engine crane tonight. Any suggestions greatfully accepted Mark | ||
| Michael Hicks Experienced User Username: bentleyman22 Post Number: 36 Registered: 12-2011 |
i have the same problem with Jaguar Engine's just make shore you put something over the windscreen as i have known of cars when they have let go smash the windscreen i just cut the stud and replace them all | ||
| Peter Talbot Prolific User Username: squerryes Post Number: 110 Registered: 7-2010 |
The head,block,and stud each have different expansion propeties so before you get drastic might I suggest: 1. Keep the stud cold with a bag of frozen peas 2. Warm up the rest by pouring firstly warm and then boiling water over the block. 3. Try again to free up the stud. This is a simple pragmatic approach and can do no harm. Peter | ||
| Jan Forrest Grand Master Username: got_one Post Number: 333 Registered: 1-2008 |
Once again this is a scenario which could respond well to the careful application of violence. A few well aimed vertical blows with a heavy instrument to the bolt head might well break the stiction of the corrosion at the bolt threads making it so much easier to wind out. As long as you don't miss the bolt head and damage anything nearby it can't really cause any other harm. | ||
| Mark Aldridge Frequent User Username: mark_aldridge Post Number: 74 Registered: 10-2008 |
Head is now off after 6 hours of rocking,vibrating the stud with a ground off air chisel, heat gun,freezer spray ,boiling water and VIAKAL limescale remover which very effectively dissolved the accumulated corrosion carbon and crud! Fortunately head block and pistons are undamaged, but the exhaust valves are heavily white deposited and one has a piece approx 1/4 inch square missing hence no compression. Rebuild probably next weekend. Mark |
