Loose Valve Cover Bolts

I suspect the reason that they loosen up over time is because of the rubber in the washer and the VC gasket shrinking over time due to the heat cycle. They aren't necessarily backing out persay but when the rubber shrinks or weakens, there is actually less tension thus causing the bolt to be "loose". I wonder why Toyota went with this type of design for these washers because other Toyotas that I've owned in the past had purely metal washers.

 

did think about using blue loctite but not in the threads, I am afraid that the bolts will break before the loctite gets loose. But you gave me an idea - if I do not find the studs. Maybe use just a little loctite under the bolt head between the valve cover and the bolt?

 

I wouldn't use blue loctite. Use purple if you have to.

 

Used these in our Chevy hotrods 40 or so years ago they worked fine

https://www.amazon.com/Spectre-Perf...=valve+cover+hold+downs&qid=1682362256&sr=8-4

But the configuration of the Taco valve covers will not allow it to work.

Was thinking of using these, with a light spring loaded washer

$7 Spectre Performance 5324 Valve Cover Mini Spreader Tab, (Set of 8)

https://www.amazon.com/Spectre-Perf...=valve+cover+hold+downs&qid=1682362256&sr=8-5

Thoughts?

 

I think I am going to buy thin lock washers - just to put enough pressure for the bolts to stay tight.

 

Jolly have you tried the Locktite or the lock washers on valve covers as of yet? I’ve got that task along with all the other oil seals, and gaskets. Going in to replace plugs, wires, coils and removal of fuel rails to r&r injectors. I want to remove all the peripherals but Once so trying to find a solution for this pesky leak as I’ve tried all the other temp nonfixes.

 

Not yet Sir. I hand tightened them snug for now until I find THIN washers, Do not want to use thick washers from HD /hardware store - as I may strip the head with not enough threads locking it, and do not want/need that.

 

In RC world we use heat to break loose blue thread locked bolts....

so using blue Loctite on anything on the engine would not be productive....


Could use hi-temp Loctite ......but the surfaces are supposed to be etched for it to work best....

and then touch em with a 75w solder iron and count to 20 before you break em again....

 

Threadlocking the bolt won't solve the issue, it's the rubber gasket shrinking over time. Very common on valve covers from that era, especially the 4.7

I just check them from time to time. Tighten down a little as needed. All manufacturers got better at gasket/sealing systems over the years. Toyota was still better than most, even in the 90s