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[yorkibob]

I drive a Jeep Grand Cherokee Lorado 2.5 TD 1997 and I get a loud screaming noise from the engine but it is only when on 3/4 to full throttle when the engine is working hard  say going up a slight gradiant - especially when towing a caravan.
The noise always begins at about 1800 RPM on heavy acceleration and is allways consitant eg.at 60mph it will scream with a lot of throttle at 80 mph it does it nearly all the time. There is nothing slipping eg.drive belt etc and since the problem has been there since I bought the vehicle 12 months ago if it had been the turbo' I think it would have packed in before now?  Anybody any ideas please.

  Bob.

[Dave69]

if it's not the belts or turbo as you mention the only other thing it might be as i had a similar sound on mine was a worn water pump. normall driving it was fine but under load it appeared to give sufficient force to move the pump impellar and cause it to fould on the pump housing. with it being directly driven by the aux belt the squeal was then the belt slipping on the pulley. when the engine was idling there was no evidence of pump wear. only when the pump was on it's final legs did the squealing start at idle speeds.

i would still check the belts for signs of polishing and wear on the grooved side

not that this is a solution to the problem

[yorkibob]

Thanks for that Dave 69,   I'll give it a check over at the weekend

Bob

[Mike Pavelin]

Check the bolts for the EGR valve aren't loose, the turbo/intercooler hoses are secure and aren't holed, the intercooler isn't holed, the inlet manifold is tight and gaskets are ok. An oily stain where there shouldn't be one may be a clue.

[yorkibob]

Thanks for that Mike, the Turbo to intercooler pipe has a lot of oil arround it, though I cant see a hole or anything (maybee it is there when under pressure) I may invest in some new pipes, the noise is only there as I say when the engine is working hard. You may have hit the nail on the head with this idea.
Bob

[Dave69]

what you might have is a bearing on the turbo starting to wear as well as the seal hence the oil as it's sucked back into the intake side. pop the turbo intake pipe off and with your fingers try and fell if there is any movement on the inpellar. also look to see if it excessively oily as there shouldn't be any being with it being the air inlet.

[yorkibob]

Hi Dave, There is some oil on the outlet pipe from the turbo' but no oil on the impeller and it doesent feel loose - giving me a headake this one.
are there any vacuum valves that may be at fault? I  have tried blocking off the EGR valve but that didn't make any difference either. a thin high pressure pipe on the turbo seems to go to a valve on the lower part of the turbo but I can't see a vacuum pipe on it? I'm thinking of temporerily blocking this off.

[Dave69]

back to basic explanation stuff now

the turbo has two sides one hot and one cold. both are joined by a free spinning double sided impellar, which is driven by the exhaust gasses exiting down the exhaust manifold. this then spins creating a variable air pressure going into the engine resulting in a higher compression. the middle bit of the turbo holds the impellar axle is fed by a direct oil feed from the engine which flows oil for cooling in the top and out the bottom back into the sump, this stops the intake side of the turbo from cooking. the faster you go the more air is forced into the engine.
 the air being sucked into the engine runs through it's own radiator which cools the air thus making it denser and better for more horse power.
 if a turbo seal is in the early stages of wear then the air intake will pull a misting of oil into the intake tract.

I cant remember if there is a vent pipe from the engine to the intake system but i have a feeling there might be. when i had mine i had oil in the pipe from the intercooler outlet, but to be honest was never to worried about it. one problem i did have was the turbo inlet pipe tended to collapse  when the turbo ran above 2krpm. this was due to the support coil failing. silicone mastic tubing is a good alternative if you have this problem.


no real solution unfortunately

[yorkibob]

Thanks for the info' Dave - as you say, no solutions but plenty of things to check out.
All imput very much appreciated
Bob.

[Dave69]

just reading the post again with the screaming starting at 1800rpm this is the point where the turbo starts to realy spin up. when driving the turbo fully comes into play from 2000rpm. does the jeep seem sluggish when driven ?

[Mike Pavelin]

I had the exact same symptoms once and it was a cracked intercooler.

[yorkibob]

- no there is no loss of power at all - the engine pulls very well even when it is screeming, thats why I dont think the turbo' is at fault it has been doing it for so long now (since I've owned the Jeep anyway and probably long before that) the turbo'would have packed in I suspect?
Having read some of the comments I am wondering if it is either a turbo hose or the intercooler. It certainly isn't affecting the reliability as I tow a caravan frequently and use the Jeep for work - a round trip of 40miles a day with 4 strapping chaps in it.
I am tempted to rig up a temporary pipe system to bypass the intercooler I know there will be some power loss but it may prove if the intercooler or pipework is leaking - what do you guys' think

Bob

[Dave69]

what you could do is take a hose direct from the airbox and straight to the turbo intake and see what happens

[yorkibob]

sorted engine noise, fault was a hole in the intercooler pipe cost was
£8-99 from ebay for an insert pipe and jubilee clips - Chrisler Jeep wanted £450 to fit a new pipe?

[Dave69]

nice to hear your sorted

[yorkibob]

thanks to all contributions from you guys = yorkibob

[Tank]

Glad its sorted,and really cheaply too,worth the tooing and froing i reckon