Kurt Posted January 19, 2016 Share Posted January 19, 2016 A while ago whilst servicing my defender i noticed that there was positive pressure at the airbox on my defender ( felt at the airbox where the little drain plug fits ). Have recemtly changed the timing belt and the symptom still remains though has become a little more rythmic , 7chuffing around two times a second. Valve clearances have been checked and adjusted along with new valve caps. Timing belt fitted correctly and checked twice since to ensure all still aligned. Runs at correct temp and no bubbles in header tank. Exhaust note possibly sounding a little boomy at higher revs under load. Also pressure definately not coming from crankcase as have disconnected breather from intake and symptoms remain.A little perplexed by this now and amy thoughts on what could be causing this much appreciated. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted January 19, 2016 Share Posted January 19, 2016 Kurt, check that you don't have a broken rocker shaft due to stripped threads in the head for the hold down bolts/studs. This sometimes happens after a broken timing belt. To check it properly you will need to remove the rocker shaft as you just don't see it with a visual check. Good news is its an easy fix with a new shaft (about £30 genuine) and some helicoils in the stripped thread bosses. HTH Mo Quote Link to comment Share on other sites More sharing options...
Kurt Posted January 19, 2016 Author Share Posted January 19, 2016 ^ Thanks for the suggestion it was something that had not crossed my mind though should have. All seems well with the rocker assembly ( whipped the cover off and removed/refitted this evening). One more thing of note is that if I remove the top intercooler hose I can hear a definite kind of metallic "popping" noise coming up through the inlet manifold and what sounds like a bit of disruptive turbulence being caused in there somewhere. Sounds "exhaust"y somehow for want of a better description. I'm beginning to think burnt seat/sticking/bent valve or a crack between an exhaust and inlet port though not sure how common this is on a 300. Quote Link to comment Share on other sites More sharing options...
g-mack Posted January 19, 2016 Share Posted January 19, 2016 hallelujah!!!!!! someone else has this problem!!!!! I have had this for 2 year and still can't get to the bottom of it! good luck, I will be keeping a close eye on this thread. does yours make a loud resonating boom? mine does Quote Link to comment Share on other sites More sharing options...
Les Henson Posted January 20, 2016 Share Posted January 20, 2016 Few things can cause this. The worst being piston blow-by. To check this just remove the oil filler cap and see if the pulsing stops and then can be felt through the filler cap hole. Other thing is exhaust/inlet gasket leaking between exhaust and inlet port. Valve not seating/cracked/chipped. Head gasket compression leak to the camshaft side of the engine. Les Quote Link to comment Share on other sites More sharing options...
Kurt Posted January 21, 2016 Author Share Posted January 21, 2016 hallelujah!!!!!! someone else has this problem!!!!! I have had this for 2 year and still can't get to the bottom of it! good luck, I will be keeping a close eye on this thread. does yours make a loud resonating boom? mine does Oh it does that most definitely unfortunately.... when under load and I can kind of drive through it most of the time conditions allowing. More of an annoyance than anything though I might just be able to detect a bit of flatness in power when it happens and sometimes with a little grey/whitish smoke to. Few things can cause this. The worst being piston blow-by. To check this just remove the oil filler cap and see if the pulsing stops and then can be felt through the filler cap hole. Other thing is exhaust/inlet gasket leaking between exhaust and inlet port. Valve not seating/cracked/chipped. Head gasket compression leak to the camshaft side of the engine. Les Thanks Les have tried the oil filler cap off and still the same! Beginning to think more and more that this is a valve timing issue as pulses of backpressure became more defined ( more of a definite "pop" than slightly pulsing draught of air ) after I changed the timing belt. One thing that has played on my mind after doing the belt change is that I developed a bit of confusion over the cam timing in that are you supposed to time exactly to the mark on the sprocket or to the peak of the tooth? The marking on mine was more to the shoulder of the tooth kind of in between the valley and the peak? Quote Link to comment Share on other sites More sharing options...
Kurt Posted January 23, 2016 Author Share Posted January 23, 2016 Other thing is exhaust/inlet gasket leaking between exhaust and inlet port. New gasket fitted today all bolts/nuts torqued to correct spec and still backpressure in the inlet..... looks like the head is going to have to come off. Oh the joys! Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted January 23, 2016 Share Posted January 23, 2016 I was going to suggest camshaft but I think the lobes would have to grow to create valve overlap ! Mo Quote Link to comment Share on other sites More sharing options...
Kurt Posted January 23, 2016 Author Share Posted January 23, 2016 ^ Actually I just had the thought that it may possibly be a seized/sticky/otherwise damaged cam follower or other part of the tappet assembly? Might be worth checking before I remove the head. Quote Link to comment Share on other sites More sharing options...
g-mack Posted January 23, 2016 Share Posted January 23, 2016 i thought about it too, but correct me if I'm wrong, if the cam lobes, followers sliders etc were worn, then that would only reduce the amount the valve could open? our problem must be the valves staying open too long or not fully closing. I've ruled out the not closing on mine as i replaced my full head with a turner AMC. Quote Link to comment Share on other sites More sharing options...
Kurt Posted January 24, 2016 Author Share Posted January 24, 2016 Went for a drive today and the booming under load appears to have gone after replacing manifold gasket ( showing evidence of leaks around inlets) and intercooler hoses which were very soft with a light misting of oil around the end of one of them. Timing case off also and belt perfectly aligned when all the pins are in. Backpressure remains however! Quote Link to comment Share on other sites More sharing options...
Nigelw Posted January 24, 2016 Share Posted January 24, 2016 God I hope we get to the bottom of this, wracking my head and struggling to think of anything not mentioned already. Quote Link to comment Share on other sites More sharing options...
g-mack Posted January 24, 2016 Share Posted January 24, 2016 Went for a drive today and the booming under load appears to have gone after replacing manifold gasket wish mine was that simple! changed mine no difference! so yours sounds fine now, do we know for definite that tdi's don't all ave a little air coming out at tick over? could other tdi owners maybe open the little rubber drain with there fingers on the filter housing and see if they feel a little air blowing? Quote Link to comment Share on other sites More sharing options...
Nigelw Posted January 24, 2016 Share Posted January 24, 2016 My 200Tdi Disco has vacuum, revved up a little it just gets stronger and circa 1400 rpm the intercooler pipes begin to swell. How sad that I actually went out after reading this to check my own engine, paranoid? A little Quote Link to comment Share on other sites More sharing options...
g-mack Posted January 25, 2016 Share Posted January 25, 2016 thanks nigel, seem to confirm then there shouldn't be air coming out! lol glads yours is all good! Quote Link to comment Share on other sites More sharing options...
Kurt Posted January 25, 2016 Author Share Posted January 25, 2016 wish mine was that simple! changed mine no difference! so yours sounds fine now, do we know for definite that tdi's don't all ave a little air coming out at tick over? could other tdi owners maybe open the little rubber drain with there fingers on the filter housing and see if they feel a little air blowing? I was mistaken. Arfter driving again today the booming is still there.... Quote Link to comment Share on other sites More sharing options...
g-mack Posted January 25, 2016 Share Posted January 25, 2016 oh no! i must admit I've had a few occasions when i though i fixed it then realised its still booming!! i originally thought it was a resonance changed exhausts engine mounts checked for anything touching etc etc. I'm now convinced it is due to the pressure out the intake! i know its defo not head or valves sticking or weak valve springs as it was all replaced. when the head was off i inspected the cam followers, rollers and brass do da's and there was no wear in them. also checked all the rods for bends. rocker is def sitting tight to head all my collets are in place and I've lost count of how many times i have checked tappet gaps!!!! took it to a bloke who "new landy's" he had a listen said it was running lovely, starts on the button no smoke blah blah. done a visual timing check (pins in fly and injector pump) said it was right but not had timing cover off for closer look. i think that will be my next move, but gonna take it to a place called spanner monkeys (pete) who does know landy's and have him replace belts and tensioners etc and take it from there! Quote Link to comment Share on other sites More sharing options...
steve b Posted January 25, 2016 Share Posted January 25, 2016 G-mack and Kurt , what airfilters etc do you use ? Std pipework or modded ? I have noticed some intake noise at tickover from some raised air intakes over the years. Maybe hooking up a cheapo vac/boost gauge to the airfilter housing would tell more ? I would think it should hover around neutral to slight vac? cheers Steveb Quote Link to comment Share on other sites More sharing options...
g-mack Posted January 25, 2016 Share Posted January 25, 2016 mine is all standard, no snorkel, paper filters Quote Link to comment Share on other sites More sharing options...
Kurt Posted January 25, 2016 Author Share Posted January 25, 2016 ^ Standard ( just replaced ) air filter with snorkel. Noise still present with snorkel disconnected. Quote Link to comment Share on other sites More sharing options...
Kurt Posted January 25, 2016 Author Share Posted January 25, 2016 Head/head gasket has gone! Noticed that it sounded a little extra raucous today and was a bit of white smoke upon acceleration away from lights this morning. Just checked the header tank and the new ( blue) coolant i put in at weekend has turned a sickly bright yellow colour! No bubbles at idle ( perhaps why i did not notice it earlier ) but a steady stream when rev'd. Had put a new mls gasket on it a year ago and it had been fine until now. Think i may have found my problem! Quote Link to comment Share on other sites More sharing options...
steve b Posted January 25, 2016 Share Posted January 25, 2016 I think you have it there Kurt , It may be worth getting the head checked for flatness and pressure tested while it's off as you only recently replaced the HG and maybe new genuine headbolts. cheers Steveb Quote Link to comment Share on other sites More sharing options...
Ex Member Posted January 25, 2016 Share Posted January 25, 2016 Check valve lash. You drop a valve cap and this is what happens. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted January 25, 2016 Share Posted January 25, 2016 Glad you found it Kurt. Mo Quote Link to comment Share on other sites More sharing options...
g-mack Posted January 25, 2016 Share Posted January 25, 2016 hope it solves it for you kurt! have you got the head off? 1 Quote Link to comment Share on other sites More sharing options...
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