Recently, the intake exhaust gasket on my 81 300 CD popped on the number 5 cylinder and needed to be replaced. Upon removing the air cleaner housing and separating it from the intake manifold, I noticed it was very black and wet inside. When I reached my hand in, I pulled out four huge gobs of sludge. Pretty sure this isn't normal.

Car has 75,000 miles on it and is all original. It received very little maintenance before I picked it up...one owner, my mother. Dad didn't believe in preventative maintenance. My suspicion is the air filter was allowed to get so clogged that it created a vacuum and just drew any oil that got splashed into the separatorinto the intake manifold.

Since I have owned the vehicle for the past four years, I've done all the required maintenance. I changed all filters, power steering filter included and I have noticed no oil consumption. I check the oil frequently and it's always full. Any insight as to why this huge amount of sludge would be in the intake manifold would be appreciated, as well as suggestions as to how to get rid of it inside the cylinder head ports. I'm afraid to use spray cleaner as I do not want to hydro-lock the engine. Brake cleaner came to mind because it evaporates readily. Thank you in advance for your help. Andrew

 

thanks!!! i never would have thought that was normal but that makes sense. i had planned on axing the EGR anyway. can you or anyone tell me the drawbacks / benefits?
i was either going the cleaner route or just going to wipe out the cylinder head portsas best i could with paper towels soaked in cleaner . since it is not as thick there i didn't think i would do harm wiping it out. the intake will be done with a combination on engine degreaser, waterand brake clean for the final cleaning.
thank you forcedinduction for your reply. was really worried something catastrophic was eminently going to happen.

 

After 3 cans of engine degreaser, 3 cans of brake cleaner, 2 cans of carburator cleaner and 1 can of intake manifold cleaner and lots of water, my intake manifold is finally clean. It took approximately 6 hours. Took your advice and did not use cleaner on the cylinder head ports, I used intake cleaner and a rag and wiped from the inside out with my finger as best I could. Looked in there with a flashlight, didn't see any big blobs of stuff, so I pretty much left well enough alone.

I also pulled the vacuum line to the EGR valve off and blocked it off. Cleaned the EGR valve and made sure it didn't leak before buttoning it all back up. Cleaned the oil separator with 1 can of brake clean and a heavy duty degreaser. It took about 4 hours to clean the air cleaner housing and oil separator. I hope to never have to do that again, because it really
[:@][:@][:@][:@][:@][:@]. Thanks for all your help, wish you were here to do it for me.

 

I found the same issue on my 83 SD yesterday when I removed the intake/turbo and exh manifolds......very clean , consistent exhaust ports, and gummed up, tar looking intakes. With 174K, I am going to do a compression test first, before I pull the head for a cleaning and a valve job and some port polishing.

The EGR is going to be blanked off after this...it's like running toilet water into your bath tub before taking a bath.........I spent 25 yrs in the Navy on Nuclear subs and we owned the diesel on every boat I served on. I never saw so much **** in an intake port like this......bye bye EGR.

 

ForcedInduction, I am aware of "port Polishing" and what it does/doesn't do......What I should have said was "clean up" my intake ports......I have never seen so much crap...I scooped up bunch from the 3 and 4 cylinder ports and just could not believe how 178K and 31 yrs managed to make such a mess. We are expecting heavy monsoon rains today/tonight in az, so I'll continue rolling the motor until I get each port cleaned. The compression test will tell me what else I want to know. I did my chain stretch test and i only have 3 degrees ATDC, so my chain and tensioner rails appear to be doing well @ 174K.

 

I got my compression test done......checked all cylinders 3 times.......here are the results:
#1 410, #2 405, #3 402 #4 400, #5 400

SWEET!
No valve job@ 174K!

 

Contrary to the FSM, I did this cold because I had so much taken off to put it all back and run to get it to 80C.

 

Cleaned a lot of nasty tar/sludge from the ports as well. Now I remove my starter and take it to the rebuild shop for a bench test to see how it is.