excessive blowby-possible causes?

[jrisingmoon]

What are the possible causes for excessive blowby? Worn piston rings? Trying to figure out what all is in store for me when I pull the heads off and replace the gaskets.

Also, if it is the piston rings, will I be able to tell which piston's rings are shot or will ALL of the piston rings need to be replaced?

I'll compression test it in the next few days and give a heads up later...

 

[EvergreenRanch]

you need to replace all of them (which you might as well while you are there) because the cylinder with the least compression needs to be within a certain range of the cylinder with the highest compression.

 

[geonc]

High crankcase pressure or blow by can result from more than just piston ring wear.

Worn valve guides

Worn valve seats/valves

Hairline fractures in piston crowns----using ether will cause this!

egg shaped cyl bores---EVERY eng will need some tuning of the cyl bores.

intake/valley pan seal leaks

blocked/inoperative CDR valve

You are better off doing a cyl holding press test than just a comp test unless you are having severe smoke, oil/water co-mingling

 

[obinella]

High crankcase pressure or blow by can result from more than just piston ring wear.

Worn valve guides

Worn valve seats/valves

Hairline fractures in piston crowns----using ether will cause this!

egg shaped cyl bores---EVERY eng will need some tuning of the cyl bores.

intake/valley pan seal leaks

blocked/inoperative CDR valve

You are better off doing a cyl holding press test than just a comp test unless you are having severe smoke, oil/water co-mingling

ok, ill give ya the cracked piston, the problematic cdr,and egg shaped bores although taper and scoring may be more common, we could through in end gap that is two large,lost ring tension, beat out ring lands,etc. but you need to splane the rest ricky

 

[Diesel JD]

George is absolutely right, but you need to be sure that you really have a problem before you tear into it, cause an overhaul, a basic one...all new piston rings, rip the engine out, full gasket set, check the heads, hone the pistons etc. will cost you $500-1000. It will be more if you must sleeve or bore cylinders and replace pistons. The correct way to check for excessive blowby is to plug all orifices in the block where crankcase pressure can escape except the dipstick, and rig up a manometer to it. There is a limit to how much is allowed per IH specs but you'd have to check with IH or a member taht knows better than I do. The eyeball test is to take off the filler cap and run the engine at idle, its not so much a problem to have a bit of blowby steam at idle, if it disappears when you rev the motor above 1500 RPM and you don't have a definite rythm to teh blowby, its not a cause for great concern. Also, don't wory about oil consumption from blowby till it is gretaer than a quart per 400-500 miles. Bottom line, don't fix this problem unless it is causing other problems or is symptomatic of a split piston. Oh and don't forget to clean, replace or ditch the CDR valve in favor of a RDT.

 

[jrisingmoon]

What would i need to do a cylinder holding press test?

A leakdown tester?

 

[jrisingmoon]

George is absolutely right, but you need to be sure that you really have a problem before you tear into it, cause an overhaul, a basic one...all new piston rings, rip the engine out, full gasket set, check the heads, hone the pistons etc. will cost you $500-1000. It will be more if you must sleeve or bore cylinders and replace pistons. The correct way to check for excessive blowby is to plug all orifices in the block where crankcase pressure can escape except the dipstick, and rig up a manometer to it. There is a limit to how much is allowed per IH specs but you'd have to check with IH or a member taht knows better than I do. The eyeball test is to take off the filler cap and run the engine at idle, its not so much a problem to have a bit of blowby steam at idle, if it disappears when you rev the motor above 1500 RPM and you don't have a definite rythm to teh blowby, its not a cause for great concern. Also, don't wory about oil consumption from blowby till it is gretaer than a quart per 400-500 miles. Bottom line, don't fix this problem unless it is causing other problems or is symptomatic of a split piston. Oh and don't forget to clean, replace or ditch the CDR valve in favor of a RDT.

Well, oil leaks were a problem BEFORE I replaced the IP. I think when I actually ran the thing I was putting EXCESSIVE amounts of oil in it every week. It may have been a gallon a week but I can't remember correctly. I've only driven it a total of two months in a year due to problems I've had with it. I was told that older engines leak oil a lot, diesels especially, but once I realized it needed a gallon a WEEK I realized something was wrong. Then I replaced the IP and something was REALLY wrong. I got back from one of my test drives and there was a healthy stream of oil leaking down the engine below the heads.

$500-$1000 for parts? I'm already looking at a full gasket set replacement so that's a not a problem.

I did replace the CDR with an RDT and that allowed me to get into 3rd gear after I replaced the IP.

 

[Diesel JD]

Sounds like your main problem is oil LEAKS, if you can see a stream of oil like that....still, you should test it for excessive blowby per IH specs or follow George's intructions on a cylinder leakdown test. If it is just leaks, it may be head gaskets and/or valve covers and the valley pan. A compression test wouldn't hurt. How about the front and rear main seals...are they sealing or leaking as well?

 

[Freight_Train]

YOUCH!Gallon per month!That is a BIG problem.I never went though more than a quart or two per 5K miles in White Lightning.Either you have every gasket leaking,CDR valve stuck shut,valve guides worn out,or a hole in oil pan.If the CDR valve is stuck closed then it would allow excess pressure in the crank case which basically squirts oil out of every joint.Valve guides,well,you would be smoking like a Freight Train if you was burning that much oil

 

[jrisingmoon]

Sounds like your main problem is oil LEAKS, if you can see a stream of oil like that....still, you should test it for excessive blowby per IH specs or follow George's intructions on a cylinder leakdown test. If it is just leaks, it may be head gaskets and/or valve covers and the valley pan. A compression test wouldn't hurt. How about the front and rear main seals...are they sealing or leaking as well?

Front and rear main seals? Of what? The oil cooler?

Where can I get a leakdown tester? I'm also looking for a 6.9 compression adapter. Any suggestions?

 

[jrisingmoon]

YOUCH!Gallon per month!That is a BIG problem.I never went though more than a quart or two per 5K miles in White Lightning.Either you have every gasket leaking,CDR valve stuck shut,valve guides worn out,or a hole in oil pan.If the CDR valve is stuck closed then it would allow excess pressure in the crank case which basically squirts oil out of every joint.Valve guides,well,you would be smoking like a Freight Train if you was burning that much oil

Well, the oil plug was the source of some of the leak but that much?

 

[EvergreenRanch]

rear main seal is the seal between the engine and the transmission. front seal im not 100% on but i think it has to do with the crankshaft and dampener at front of engine. get a new washer for the oil pan plug, should solve that issue. clean up were the oil leakage is heaviest and then run engine and that should shed some light as to where your issues are.

 

[tonkadoctor]

What are the possible causes for excessive blowby? Worn piston rings? Trying to figure out what all is in store for me when I pull the heads off and replace the gaskets.

Front and rear main seals? Of what? The oil cooler?

Front and rear main seals? Of what? The oil cooler?

Whoa here guys!!! Front and rear main seals are the front and rear crankshaft seals on the main journals.

Before even thinking about replacing the head gaskets and every other gasket in the engine you need to get heavy into the books and/or get some professional help that can mean the difference of your engine running 10 seconds or 10 + years or your truck becoming a frustrating "project" that never gets finished. Now if I've misjudged your knowledge on rebuilding engines based on what I have read please accept my appology.

Trust me when I say that the slightest innocent mistake rebuilding an engine can ruin your day and pocketbook within seconds of firing it up. I've rebuilt hundreds of engines over the last 25 years and have had one throw a rod in the 1st few seconds and another blow a head gasket after about 10 minutes both times due to an incorrect torque on on bolt and can say for a fact it's a sick feeling.

bad CDR or cracked / bent top rings are in my opinion the most common culprits. Compression or Leakdown test is the best way to determine the condition or the engines internals.

 

[geonc]

What would i need to do a cylinder holding press test?

A leakdown tester?

That's it! for the confusion of terms.

Using a leakdown tester will isolate the source of crankcase pressure.....hearing the air from the intake/exh would identify valves/guides etc.... while air from the base pan/dipstick would identify rings/pistons etc.....

In the final months of my '90 IDI's well hammered 300+ k mi life, I was adding a gallon a day yet the 'ol girl NEVER failed to light off after a couple spins

And on the other side of oil consumption, my '93 IDI that I put 225 k mi on in 4 years was barely using 4 qts every 5 k mi

BTW...both were natural asperated

 

[jrisingmoon]

Summit has a leakdown tester part # SUM-900010. It has 14mm and 18mm adapters. Do I need those and do I just use the glow plug adapter that goes with the compression gauge?