I lost an intake manifold bolt down the distributor hole. I tried to fish it out with a magnet and could not do it, soooo I reassembled the engine and now it seems to have low oil pressure (10-12 psi vs 30-45 in the past)

Any ideas? I know about all the critics here, if I just tell you all your right before you beat me up - can I skip the "you should have" part??
I can not get to this bolt from the top - Can I access it through the bottom??

Thanks

 

I definitely wouldnt start the car anymore! If you have lost oil pressure already, It might already be to late.

 

You should be able to drop the oil pan from under the car.

Are you getting any noise from the engine? The bolt should have dropped to the bottom of the pan...still not a good thing.

 

Appreciate the optimism

 

The oil pressure drop could be unrelated to the bolt(maybe). And if you drop the pan you can put a new oil pump on. idk why you had the dist/intake bolt out and the reason could lead to the pressure drop. Say for example I assume you swapped the intake and when reinstalling the intake you ,may have used too much permatex and it came loose and is clogging the oil pickup and that's why you lost pressure. Have you changed your filter since w/e you've done? Anyways with the pan off you'll have an idea what's going on.

 

I don't understand how you could have seen a pressure drop. Oil goes into the pickup in the bottom of the pan through a screen. I guess I'm just saying it doesn't make sense if you think about it? It could run fine for a long time, or it could create havoc.
Also, if the bolt is in the lifter galley pulling the pan is a waste of time. Got any friends with cameras?

 

I Agree. If its not in the lifter valley then it has to be in the pan. Most stock sbc engines that I have owned ran 15-20 psi at operating temp.

I would pull the pan and get the bolt out.

 

I replaced a head gasket. The Oil pressure was high and dropped (the bolt shifted around??) It could be unrelated.

The top of the lifters is exposed - It might be in the bottom. Where does that distributor hole go? It is forward and has a blind curve.

 

This is on a L98 right?

I wonder if the bolt isnt down around the oil pump intermediate shaft? Correct me if I am wrong but I dont believe the distributor hole goes straight to the pan. The distributor drives the oil pump with the help of the oil pump intermediate/drive shaft. You should beable to get to the bolt from the top.

 

There is a rare chance the bolt did any harm and it's prob siting in your oil pan. Try a new oil pressure gauge 1st maybe. Are you using the stock gauge? If so what's the milage? Can't believe I didn't or no1 else mention that before.

 

Did you actually pull the intake back off and see if it is sitting in your lifter valley? Id be willing to bet it is.....

I just dont see how you would get the distributor back in if a bolt fell down there..

 

Just took these pics, it's a one peice nonroller 350. 1st pic is top, you cna see it's roomy, 2nd pic is from the bottom and you can see the top of the shaft look for the slot at the tip. The oil pump driveshaft goes threw the cap and block and no room for a bolt too get in those holes with it.

 

I don't know if there is a tighter clearance on the L98. But years ago I was rebuilding the 350 in my 74 Blazer with my 4 year old son "HELPING". I had everything ready....only had to drop the distributor back in. I could not find the hold down bolt. I finally looked down the distributor hole and could see that it had gone past the oil pump shaft and was sitting in a position so if I had turned the crank, the crank would have hit the bolt. Tried fishing it out with a magnet (magnet was not worth the $10 I spend on it in 1976!) and the bolt dropped into the pan. I had to drop the pan.

My advice....never let your 4 year old son help build an engine!

 

Bet the oil pressure loss is a result of the blown head gasket. Coolant doesnt like bearings.

what size was the bolt? Bet it has nothing to do with your oil pressure at all. Its either sitting in the valley or bottom of your pan probably wont hurt anything but check.

 

I would have never started an engine with a bolt inside it!

 

So to answer the questions

Are you getting any noise from the engine? Runs a little rough, but it is hitting on all cylenders and seems OK

why you had the dist/intake bolt out – Chasing threads in preparation of reinstalling the intake

you may have used too much permatex – Maybe, but the only place I used the liquid gasket was on both ends of the valey

doesn't make sense – I agree – It seems that a bolt would drop to the pan, but I do not know

lifter galley pulling – Where the lifters and pushrods meet does NOT have the bolt – it is lower than that

I wonder if the bolt isnt down around the oil pump intermediate shaft? Correct me if I am wrong but I dont believe the distributor hole goes straight to the pan. The distributor drives the oil pump with the help of the oil pump intermediate/drive shaft. You should beable to get to the bolt from the top. – I was not able to get that bolt from the top – It is not visable and it seems to be forward on the distributor hole.

Try a new oil pressure gauge - Makes Sense, I am using the 25 year old stock gage, The mileage on the engine is 25K, the car 125K

Did you actually pull the intake back off and see if it is sitting in your lifter valley? It is lower than the lifter tops, it is not visable

I just dont see how you would get the distributor back in if a bolt fell down there.. – Lots of room on all sides

The pictures are very helpful

what size was the bolt? It is the manafold bolt with the torx head – maybe about 1.5 inches and about 12mm of ½ inchs

Questions not asked – Oil is up to full, It could be the gage sucked up some dirt and there is no pressure issue, but a pressure reading issue.

 

I would not run that engine anymore until you retreive the bolt.

 

I remember once I dropped an M4 metric screw into a toyota corolla engine. I heard it bounce a couple of times and hit the bottom of the oil pan (it was empty since I had drained it for an oil change). I left it there in the oil sludge with no ill affects. Put a magnet on the oil pan just in case that bolt drops down and it will simply be captured by it until the engine is ready to come out for other reasons.

 

I use a bead of permatex on the ends for the intake too, but I make sure it cures 24hr before I fire it up so it's nice and solid. If your not good at just setting the intake on and move it around alot you might end up with some squeezed out kinda far. One of my 1st engines that I trid a few diff heads and intake combos on I ended up with some of that intake permatex in the oil pick-up. A pretty big peice about 4" long and maybe a 1/4" at it's widest. Now this was a stock style pickup with the halfcup and I saw no diff oil pressure than I was use to, from the 1st time I put that engine together and the last time I took it apart, but if you got enough permatex it could happen. And I've herd a engine builder complain of it happening when people use too much, but I imagne intake placement has part to do with it, because as I mentioned earlier I remeber the color of the permatex in my pick-up and I used that color(non-black) in my early days and I rem having a hard time geting the intake positioned and having to slide it around some.

Still I'd try the gauge 1st with those miles and if it's a stock gauge they are know to not be that acurate(told to me by a gm proving grounds engineer about the c4's, last week). You need 10psi per 1000 rpm, I've drove/raced cars that idle 10-20 hot, but I like a little more.

 

Also another important question is your low pressure just at idle or the whole time?