Don't know the difference - leak or ??

[ParadiseMJ]

My truck (88 MJ 4.0 4x4 SWB) has a knock, or more accurately a tap. I'm trying to tell the difference between some valve (rocker arm) clatter and an exhaust leak. It sounds like it's coming from the front of the engine, louder when cold, quieter or non-existent when up to temp.

 

There is eveidence of a weld at cyl. #1 on the ex. manifold

 

At this point I've changed the oil twice in a month, mostly because I didn't know when the PO had done it last but also because it sat for ~1 year in his barn. It fires right up, runs well and smogged just about perfect.

 

So my question is: Is there an upgraded manifold, all I've seen are for 91 and up for headers, but not for RENIX engines.

[jimoshel]

I have seen both regular exhaust manifold and headers on EBay for renix Also Quadratec and J.C. Whitney. I'm sure a local speed shop or parts store could get them for you. You might want to use the rubber hose trick to find out for sure what the noise is and where it's coming from before spending money. My guess would be a lifter as they usually quiet down as the engine warms up whereas a leaking manifold gets louder.

[comanche12]

maybe try adjust the rocker(valve system) more accurate? like adjust it while its hot(in operation temp.)

 

try replace exhaust gasket? possible warped?

 

edit, adjust the rocker is pretty easy tho which i did alot on chevy 350 v8 often everytime after replace the cylinder heads for performance reason

[jpdocdave]

no adjustments on 4.0 valve train.

 

i had problems finding an exhaust manifold for my renix, the updated style with flex pipes built in was for ho only. I had a reputable welder weld mine, and its lasted for 2 years so far.

[comanche12]

well i means like re-tq the rocker nuts?

[88SporTruck]

Make sure the exhaust manifold bolts are tight and that the lead "donut" gasket where the manifold connects to the exhaust pipe is good.

[comanche09]

I got an OEM replacement one from rockauto.com a few months ago for around $90 shipped (they had a few left on clearance). I have yet to install it.

 

My truck has a tick at around 2000-2400 RPM. I know the manifold leak is at the rear cylinders because white smoke came out from around there when I did a seafoam treatment.

 

The manifold bolts are know to work loose on their own. Have you checked their tightnes?

 

I know that when I get around to installing my new manifold, I am going to add a flexpipe somewhere in the downpipe to relieve the stress.