another blow by question

franklin40

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so i've had a 1hdt swapped into my fj62 for about two years now. i was told by the guy who bought the engine and did the swap for me (hilltop cruisers) that it had 120000km on it (it however has 450000km written on the front of the valve cover so i don't know what that means. my truck had about 450000km on it when it was swapped in). when i got it it had a little blow by but nothing that really impressed me too much. a little oil down the side of the valve cover and onto the exhaust heat shield but nothing that ever left a mess on the floor. now i have had the injectors rebuilt and an intercooler installed and it boosted to about 16 psi max but it runs between 6 and 12 most of the time. i did a compression test and all cylinders were within 40 psi of each other but were between 450 and 490 psi (from what i've read that's a little low).

now after this past summer pulling a trailer i have a ton of oil coming out the valve cover breather. it's leaving a huge puddle on the floor after just a day of driving with no trailer. i never over heated but did see my engine temps climb to the point i had to slow down to keep from over heating. my egts were constantly between 1000 and 1100 for about 5 hours. it was a stiff hot head wind!!

so with that story in mind what have i likely done damage to? all the oil is coming from the breather for sure. the oil cap doesn't blow off if i let it sit loose on the cover but do i have to rev it to test it properly? what other tests should i be doing? i have a mishimoto catch can with baffling in it but it's not helping. i'm looking to get a provent 200 for the time being to stop the mess but that doesn't address the cause. i don't feel i'm lacking power but it may be a little sluggish compared to before. hard to tell. it's smooth with no knocks either. am i looking at needing a rebuild sooner than later?
 

roscoFJ73

 
 
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i was told by the guy who bought the engine and did the swap for me (hilltop cruisers) that it had 120000km on it (it however has 450000km written on the front of the valve cover
its hard to imagine someone would write 450k on the timing cover when its only done 120k

What happens if you take the dip stick out while its running?
 
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Have you done a leak down test?
Same as a compression test, but after bringing a cylinder up to pressure, leave it sit for 20 minutes, pressure reading shouldn't change. If it drops, your compression rings aren't sealing.
To confirm, Add a teaspoon of oil into the cylinder, redo the test. The oil can help seal the ring to confirm it's rings, not valves leaking.

Leaking compression rings can be the source of excess blow by.
Leaking could be due to ring wear, or cylinder bore wear.
 
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Ok, so your engine has a lot of kilometers on it...when they start to wear down the valve seals go, one thing to do (if allowed by the law there) is take the hose that goes from the valve cover to the air filter and have it blow out of the engine bay...or you could just unplug it and see if a lot of smoke comes out of it...there may be a restriction (hose) and a lot of preasure is going to the valve cover (bad seals or bad piston rings), nowhere else to go out, starts leaking...BTW 3 types of smoke you should always know about...1-white, car burning water...2-blue, car burning oil and 3-black, only diesels and low air or too much fuel
 
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Ok, so your engine has a lot of kilometers on it...when they start to wear down the valve seals go, one thing to do (if allowed by the law there) is take the hose that goes from the valve cover to the air filter and have it blow out of the engine bay...or you could just unplug it and see if a lot of smoke comes out of it...there may be a restriction (hose) and a lot of preasure is going to the valve cover (bad seals or bad piston rings), nowhere else to go out, starts leaking...BTW 3 types of smoke you should always know about...1-white, car burning water...2-blue, car burning oil and 3-black, only diesels and low air or too much fuel
Diesel can burn all three colors too (white/blue/black). Smell is a easier way to discern burning coolant, oil or diesel.
 

franklin40

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so i pullled my dip stick while it was running and i got a puff of pressure and then oil started spraying at me. thanks for the heads up on that one guys;)

i guess i should do a leak down test next. seems like i'm getting excessive crank case pressure. i have the hose that goes from the valve cover disconnected to a catch can that is then vented to atmosphere. still loads of oil coming out the breather

no smoke at all except at low RPM with a heavy peddle. i've got it tuned well fuel wisei think. no white smoke or blue smoke at all. just black puff shifting gears then it clears
 

franklin40

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well i guess ill put a better catch can on for now to stop the mess. it's my daily driver so i need to fix up my summer car and then i can rebuild the engine over the summer. bummer. i figured this might be the case. oh well
 

doug720

 
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As mentioned earlier, have you checked to make sure the existing crankcase vent breather and line are not blocked, and/or that the new catch can is of sufficient capacity to allow pressure to to be vented?

All engines have some crankcase pressure. If the breather is damaged or blocked, or the catch can is too restrictive, the pressure will go somewhere, ie...dip stick!

I hope it's something easy to fix.
 

franklin40

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alright then. ill double check that! i was thinking the ProVent 200 catch can. will that be enough do you think? i have pulled off the valve cover and it's only about a foot of hose coming out so i know there aren't any blocks but maybe my catch can is restrictive
 

doug720

 
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For a test, run the engine with the breather hose open to atmosphere - no catch can, and check dip stick tube for pressure. If there is still a lot of pressure, check the vent tube where it exits engine for a problem. Some engines have a oil separator type vent and maybe it's blocked?
 

franklin40

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For a test, run the engine with the breather hose open to atmosphere - no catch can, and check dip stick tube for pressure. If there is still a lot of pressure, check the vent tube where it exits engine for a problem. Some engines have a oil separator type vent and maybe it's blocked?
do you mean the vent tube off the side of the valve cover or is there another vent tube somewhere?
 

doug720

 
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I'm describing the main tube that vents the engine and connects to the catch can.

They usually are connected to the valve cover or possibly the side of the engine, and are about 1/2" to 1" id. in size.

I would disconnect at the catch can end of the hose first to see if it is passing pressure. If not, disconnect at the engine end and check for venting. If still not venting, remove the valve cover or whatever the cover the hose connects to to see if there is an internal blockage.
 

franklin40

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right. that's what i thought. i have taken the valve cover off when i put the catch can on and checked inside. no blockage at that time. ill check the hoses though and ill run it for a bit with it disconnected at the valve cover. makes sense that if i'm too restricted at the vent that ill be making more crank case pressure. what confuses me is that i'm hoping to have less oil leak by opening of the flow of where the oil is coming out of!! i guess i just don't understand the pressure gradients within the engine we'll enough :)
 

doug720

 
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Less internal pressure will result in less oil being forced out of the engine seals, gaskets, etc.

Did the valve cover have any type of valve on the vent tube barb? My Isuzu has a baffled section inside the valve cover to reduce the amount of oil mist that it vents. Check for something there also.

Hope you find it.
 

franklin40

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the valve cover has a splash guard over the vent exit inside but nothing blocking it there. no other baffles on it
 
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You might want to temporarily run a piece of hose, rug it to drain in to an open soft drink bottle etc so you catch any mess, but create no back pressure
 

franklin40

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so i pulled the hose off the valve cover going to my catch can. there is a steady but mild stream of air blowing out. no oil coming out yet after only running it a couple minutes. i checked my dip stick and no rush of air and no spraying oil!! i wonder if my catch can is too restrictive and is pressurizing my engine after all. it was on a cold start up too which is when i'd imagine i'd have most blow by (other than at high boost i guess).

ill run it like this for a day or two and see what happens
 
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