Sanity Check on my Oil Leak Diagnosis

[Gordolordo]

I need a sanity check on my oil leak diagnosis. 1995 Land Cruiser HDJ81 with the 1HD-FT engine.

After a routine oil change, I developed a pretty fast leak underneath the front of the engine. I suspected it was the front main seal (28 years old) and/or the FIPG on the timing gear cover, so I replaced both.

I put everything back together, and lo and behold, I still had an oil leak.

I figured I must’ve smeared the FIPG when I replaced the metal timing *gear* cover, but when I remove the plastic timing *belt* cover to check, oil poured out. The FIPG looked good and didn’t have any obvious leaks, and I did not see any oil leakage around the front main seal.

On closer inspection, it appears as though I failed to install the plate washer (see first attached photo) that goes between the tensioner pulley and the timing gear cover. I think my FIPG was good and the oil was basically just coming out through the screw hole for the timing belt tensioner that I have circled in yellow on the second attached photo.

Can someone give me a sanity check on if that would most definitely cause a pretty significant oil leak?

 

[TheBussman]

shouldn't be any oil coming out of that hole. There is a rubber o-ring between the oil pump and the block i would check that. but i think the only way to have oil leak into the timing belt cover is from the cam seal or injection pump/timing gear seal

 

[Gordolordo]

shouldn't be any oil coming out of that hole. There is a rubber o-ring between the oil pump and the block i would check that. but i think the only way to have oil leak into the timing belt cover is from the cam seal or injection pump/timing gear seal

So keep in mind this is the 1HD-FT engine. This doesn’t have an oil pump right behind the harmonic balancer like a 1HZ. Behind the pulleys is a metal plate that covers all the timing gears, and that whole cavity is full of oil. So right behind the timing gear cover is a big sopping oily mess. That bolt hole goes right into that mess.

 

[TheBussman]

yea there is oil in the gear case but that bolt hole should be on the outside edge of the gear case. Pretty sure all the 1h/z/dt/ft/fte motors have the same oil pump that uses a rubber o-ring that seals to the block.

might be possible that installing that bolt without the washer made it too long and pulled the outer section of the gear case away from the inner part of the gear case and caused the FIPG seal to fail, then it could leak though that hole. if you remove the outer part of the case you could take a look and see if there is a mark on the inner case.

 

[mudgudgeon]

I need a sanity check on my oil leak diagnosis. 1995 Land Cruiser HDJ81 with the 1HD-FT engine.

After a routine oil change, I developed a pretty fast leak underneath the front of the engine. I suspected it was the front main seal (28 years old) and/or the FIPG on the timing gear cover, so I replaced both.

I put everything back together, and lo and behold, I still had an oil leak.

I figured I must’ve smeared the FIPG when I replaced the metal timing *gear* cover, but when I remove the plastic timing *belt* cover to check, oil poured out. The FIPG looked good and didn’t have any obvious leaks, and I did not see any oil leakage around the front main seal.

On closer inspection, it appears as though I failed to install the plate washer (see first attached photo) that goes between the tensioner pulley and the timing gear cover. I think my FIPG was good and the oil was basically just coming out through the screw hole for the timing belt tensioner that I have circled in yellow on the second attached photo.

Can someone give me a sanity check on if that would most definitely cause a pretty significant oil leak?

View attachment 3623024

View attachment 3623026

I believe that hole goes through to the block, and would not be open to oil. I am not 100% certain though

Pic below is of the back side of the timing cover with that hole circled. It's outside of the FIPG seal line, and doesn't have a groove around it. I think Toyota would have the FIPG wrap around this hole if it was sealing in oil oil

Pic is a late model 1hz timing cover, but I believe it's essentially the same as 1hd-ft

 

[Gordolordo]

I believe that hole goes through to the block, and would not be open to oil. I am not 100% certain though

Pic below is of the back side of the timing cover with that hole circled. It's outside of the FIPG seal line, and doesn't have a groove around it. I think Toyota would have the FIPG wrap around this hole if it was sealing in oil oil

View attachment 3623821

Pic is a late model 1hz timing cover, but I believe it's essentially the same as 1hd-ft

And this is exactly why I asked.

Thanks for the hook up. I was going to chance putting everything back together if I thought that the washer might be the culprit, but you saved me a TON of time by showing me that that bolt hole was outside the gasket.

It was the FIPG that I goofed up. As soon as I took the cover off, I could see I had totally smeared the gasket all over the place when I reinstalled everything last time.

 

[Gordolordo]

Well, the oil leak is not fixed and I have more going on now. Or rather, I just noticed something else that may have been there the whole time along with my oil leak, but I missed it previously.

First off, thinking the oil leak may have been coming from the timing gear cover, I replaced all the seals and re-did the FIPG gasket. Everything seemed to be working fine. I ran the engine for a while, did not see any leaks, and figured everything was good.

Thinking my work was complete, I stopped the truck on a level spot to check the engine oil level and upon pulling out the dipstick, noticed exhaust fumes coming out of the dipstick pipe. Clean, normal exhaust fumes - no blue or white. I then replaced the dipstick, opened the oil fill cap, and did a rudimentary test with a small piece of cardboard about 2" by 2". It hovered in little puffs roughly timed to the engine running. I also noticed that this exhaust gas buildiup in the crankcase only happens once the engine is hot - on first startup and for the first few minutes, no puffs.

Second thing, the oil leak is NOT fixed, and is leaking at nearly the exact same spot as before I did any work on the truck. Additionally, that leak only starts once the engine is hot, just like the exhaust gas leak.

So, I'm thinking that both the oil leak and exhaust leak are related, and perhaps is indicative of a leaking head gasket. I wouldn't say *blown* yet because the exhaust blowby isn't huge, but once the oil gets hot and becomes thin, that is leading to both the exhaust leaking into the crankcase *and* the oil leak source that I've been trying to track down.

Anyone have any thoughts on this? I understand it could be some other things that should probably be diagnosed with a compression test and leakdown test, but the coincidence of both the exhaust and oil leaks occuring near simultaneously once then engine gets hot seems telling to me.