406 TD Engine overhaul
Moderator: RichardW
406 TD Engine overhaul
Hi, my 406's dead..engine turns over well but wont fire..got AA to look at it, and a garage...seems to be something major. I took engine out with intention of replacing the unit but was let down by supplier so thought I would tackle a rebuild of the top at least. Con rods seem ok but was told it ccould be shims which affect valve clearances.I've rebuilt a few petrol engines but not tackled a diesel. Garage did a compression test aand said it was all over the place...I know if the clearances aren't right I haven't got a cats chance in starting it so any advice where to start would be great. many thanks for all previous info supplied.
Well, the first good news is that the shims are pretty easy to tackle, and you dont even have to take the head off. Im assuming (more fool me) that its a front mounted intercooler, with and Inlet manifold that curls over the rocker cover. If so you'll need to get this off, and its the hardest part of the whoel thing! Then take the rocker cover off. leave the cambelt on and the cam shaft guides in place. With the battery disconected, and the front wheels off the ground, stick the car in 5th. you can now rotate the passnegerside wheel and you should find the cam will turn. What you want to do is have each cam in turn pointing straight up, and measure the gap between the tappet and the cam follower(bottom bit) with a feeler guage, do this for each tappet/camfollower, making sure to write these down clearly. Then Put pins in the timing pullys (cam shaft, pump and flywheel (trust me you REALLY want to do it!). Loosen the cambelt and take it off. Unbolt the camshaft and put it to one side, lift each tappet and retrieve the shim, measure the shim! you then need to compare each shim to the gap measured earlier. This will enable tyou to calculate the thickness the shim should be! Its not a difficult task but will require a feeler guage and a micrometer. If you dont already have it then the Haynes actually has VERY good instructions for this, so well worth a read, and probably better instructions than i have given!
If nothing else it will give you an idea if the clearances are the problem. But it sounds unlikely that its the shims, they dont just suddenly change uless there is a bigger problem, like the valves beign busted! But the valves dont tend to die unless you do something stupid with them! Its more likely the head gasket has gone, or a cylinder cracked. These would both create weird pressure readings! It might be worth having a search for head gasket in the Citroen area (same engine!) should help diagnose the problem. The first time i have ever done work on any top end was much the same after replacing a bent valve and all in all it was a pretty easy job!
If nothing else it will give you an idea if the clearances are the problem. But it sounds unlikely that its the shims, they dont just suddenly change uless there is a bigger problem, like the valves beign busted! But the valves dont tend to die unless you do something stupid with them! Its more likely the head gasket has gone, or a cylinder cracked. These would both create weird pressure readings! It might be worth having a search for head gasket in the Citroen area (same engine!) should help diagnose the problem. The first time i have ever done work on any top end was much the same after replacing a bent valve and all in all it was a pretty easy job!
many thanks for the info. i had the drive belt changed but it went after about a thousand miles. The cam had split into 3 bits so i had it rebuilt (top end) the head was gone so i was told they had put a citroen head on as they were the same. He also said the turbo had been a bit iffy but had freed it up a bit. It was never as good when i got it back and it smoked a bit (greyish blue) which seemed to disappear when it was revved. I replaced the rubber fuel bulb as the original was returning fuel to the tank. It was always bad starting, even before the belt went but was even worse when i got it back. The garage werent interested as they did it cheap thru an old schoolmate so i carried on with it. Eventually it broke down adn wouldnt start. AA didnt have a clue nor did a local Citroen specialist so i got it towed home. That was last october and its been sat there since as i had bought a little runaout till i got the pug fixed. once again thanks for all the help. Any more advice gratefully recieved and will contemplate working on the shims unless you come up with anything else.