I snapped the head off of one of my intake manifold bolts. My manifold has an “X” designation on it indicating 4 lengths of bolts are used, the odd one being at the right front engine lift hook. The one that snapped was in the 1-4 sequence locations at the middle of the manifold.
Now my 4100 is an 83 model and the bolt set used for the manifold use two washers per bolt.
After spending some time searching my local u-pull yard, tearing into 4100’s; an 84 and an 85 to be exact; I discovered a discontinuation of the use of washers on the manifold bolts on the later models.
I compared the newer bolt with my originals and found my original was slightly longer to accommodate the thickness of the 2 washers and the bolt head differed slightly, other than that their identical.
So far I had been unable to find a match.
Can I use the newer bolt sans the washers as a replacement for the one broken older bolt with washers?
DOES IT MATTER?
This happened to me and I bought a replacement bolt at ace hardware and just swapped the original washer onto it.
Fourth bolt from the left, front bank:
No problems so far...
They are called spring washers I believe. Upper is a regular flat washer, lower is the special one. FSM says to replace the springers but I didnt since I had no clue where to get them and no time to do it.
The intake manifold bolts with the spring washers where part of an Intake Manifold Re Seal Kit that was used to correct a problem with leaking intake manifold gaskets. There is a Technical Service Bullitin covering this retrofit. The kits where around $100 and included the bolts with spring washers and 2 updated intake manifold gaskets.
The kit kept the gaskets from being crushed from thermo cycling by allowing the manifold to float a bit more than originally designed. These 4100 blocks move around a Lot!
Spring washers should generally not be re used but in your instance just get a bolt the correct lenth and re use the washers. You should be fine.
I've reused the washers every time so far. Generally, they are just fine as long as they weren't previously overtorqued. If you've broken bolts on disassembly, I'd say previous overtorqing is a pretty good possibility...
If it were mine, I'd try to find replacement washers. Do-overs down the road are no fun.
The curved washers are called Belleville washers. The intake bolts came in two different generations, with a switch sometime around 85 (my 85 FWD had the 2nd generation hardware but the FSM showed the 1st gen reference). The later generation uses lower torque values, because the washers do the work instead of the bolt cap. They are all out of production and not available. Get on mcmaster.com and find a comparable bolt, and move the washers over. Or use a good set from the junkyard. The literature prohibits reuse but you're out of other options. I reused a set from the junkyard and its been fine.
(my 85 FWD had the 2nd generation hardware but the FSM showed the 1st gen reference). The later generation uses lower torque values, because the washers do the work instead of the bolt cap.
Problem! No information as to what the (second generation) lower toque values are suppose to be. Probably why I snapped my bolt, going for the (first generation) toque values listed in my books.
I think I will snag a complete set of (first generation) bolts from the salvage yard and use them.
Any one have a copy of the tech sheet covering this issue? Part number?
How about what the lower toque value is? (second generation w/washers)
Just for future information, rock auto has the re seal kits available. Although they are not cheap. They come with the Taps to lenthen the threads in the heads to allow a longer bolt. They also come with special re enforced composit intake manifold gaskets and bolts with spring washers.
The reseal kit is obviously the best way to go. $100 is cheap insurance.
When I compare one of my spring washer bolts with an original bolt from a donor I’ve noticed mine is fully threaded where as the original one only has about ¾” of thread.
Since my engine already has seen a reseal kit in its past, the threads more than likely have been tapped accordingly for the longer bolts.
I call my local ACDELCO out of the YP’s gave them the part number aeronca36606 posted (3634742). They located a couple of the manifold re-seal gasket/bolt kits, one being about 120 mi from me in an auto repair shop in North Idaho. They gave me the phone number of the shop and when I called they said, “yep, got one, been hanging on the wall for 20 or so years", and he’d let me have it for 75 bucks plus shipping. It list for $125.
I should see it tomorrow via UPS.
FIG-7_30 intake manifold.jpg
My 83 Eldo 4100 manifold has an "X" designation and uses 4 bolt lengths. My manual lists them as ABC & D and 22 lbs as the torque spec. 1-4 to 180 in/lbs 5-16 to 22 ft/lbs, then 1-16 to 22 ft/lbs. (see fig)
The #15 bolt (A) is the longest.
I suspect because the lifting hook attaches at that location.
Bolts 1-4 are (B).
Bolts 12,13 & 16 are (C).
The rest are (D).
The Bellville washer/bolts that were on my car corresponds with the 4 lengths listed.
I went to torque bolt #1 to 15 ft/lbs when it broke.
I caught in your thread that torque for the Bellville bolts is quite a bit less.
If the reseal kit I ordered only has the three lengths included I’ll just omit the lifting hook.
True to their word, I recieved my reseal kit today.
The kit has everything I need including instructions and extra bolts for the different configurations.
We're experincing a severe cold snap right now so the project is on hold till it warms up a bit, at least 30 degrees. GASKET.jpg