I am getting my valve covers resealed and nee to know if the guides are in there

[stewartdrums]

I have a 90 Q45 and was wondering if the timing chain was under the valve covers and if I could go ahead and get my mechanic to replace the guides. I do know that the intake manifold has to come off to replace the drivers side valve cover sealant so it will already be a costly job. Do I need to replace the both chains as well as the guides or are the guides sufficient. I read in one post something about going ahead and replacing the front seal when you replace the timming chain. Does that mean that the guide is at the front of the motor and not under both valve covers? I am hearing a little rattling noise comming from the passenger side valve cover and A slight bit from the passenger side. Does that mean my timming chain is about to go out or am I hearing the guides. Also when I crank my car I hear a rattling noise that only rattles a little then it stops then again until the car warms completely up. I have heard it a few times even when the car is warm. My engine runs fine, it idles well and doesn't run rough at all so I don't know what this is? I am thinking the rattling I am hearing is comming from the timming chain because it definately sounds like it is comming from inside the engine. If it is the timming chain or guides I am hearing am I damaging my engine by continuing to drive it thus far? Different subject: My oil pressure switch is leaking oil from it. I was wondering if that means it is not working and in return not circulating the oil correctly through my engine. Thanks

[DAEDALUS]

There is some labor overlap, and now would be a good time, but it is probably a healthy amount of additional work and cost. The guides are behind the front engine cover, so the belts and pulley have to come off as well. The chains are probably good for 250k, so replacing them depends on miles on your car and how much you drive. If you're doing the guides and covers, it's probably a no-brainer to have the chains done unless you have very few miles on the car. These items have to come off to do the chains, so if you're going to keep the car for a while, bite the bullet now and pay for the parts. If the rattle is indeed coming from the covers, it's likely not the guides or chains, but it needs to be looked at. Resealing the covers gives a great opportunity to do so. Not sure about the oil pressure switch. If it wasn't working, you would probably get a red oil light on the dash. Probably just needs to be replaced, and the part and labor shouldn't be too much.

[Q451990]

The rattle DEFINATELY needs to be addressed. That's not normal. I wouldn't spend the $$ on valve covers if you aren't prepared to replace the guides - no point in having a well-sealed scrambled engine. The plenum (aka intake manifold) doesn't have to be removed to reseal the rocker covers (or replace the guides).

The noise typically cited for chains is a "flutter" at start-up, heard from the front of the engine. In most cases there isn't a noise though - just the sound of valves and piston heads hitting each other for a split second before the engine is toast.

Heath

[stewartdrums]

You stated that the plenum didn't have to be removed to reseal the rocker cover. Is the rocker cover the same thing as the valve cover? I was told that the intake has to be taken of to do the drivers side valve cover seal. I am not a machanic but I looked at it myself and didn't see any way possible to remove the drivers side valve cover with out removing the intake manifold. I was quoted $280.00 to reseal the drivers side valve cover. Does this sound about right? Also I took a flash light and looked into the cracks of the intake manifold (plenum) and saw water leaking from a metal pipe (appeared to be a small copper pipe) running into the fire wall in the very center of the fire wall. I have noticed now that my water level in my radiator gets a little low from time to time. It seems the leak stops once the car is warm. Do you know what this is comming from?

[DAEDALUS]

Rocker cover and valve cover are the same. The intake hose does have to come off; Heath was talking about leaving the intake plenum (metal octopus) on, though I somewhat disagree; I believe your plenum does have to come off, but it depends on how old and brittle your hoses are. It comes down to the single bypass hoses at the rear corners of the covers which run down under the plenum into the V-valley. If they're not too old, then you can pull the fitting out of the cover before removing it and the plenum can stay on. In your case, I expect that the hoses are so brittle that if you pull on them enough they will shatter rather than bend. $280 sounds reasonable to me, and I'm a cheap DIY guy. I doubt that includes removal of the plenum, though, so find out what they're going to do about the hoses at the back of the covers. The passenger side is easier, so hopefully will cost less.Not sure what plenum cracks you're looking into, but any leaks must be fixed. Are you looking at the throttle body? Or is it possible the water is just condensation from the AC system? ???

[DAEDALUS]

Just for reference, Q45tech has stated that T3 charges $500 to do both covers, and another $600 to replace all under-plenum hoses. If you're paying that much, hopefully your mechanic is comparable in experience and proficiency.

To emphasize Heath's point, please have the guides done ASAP. I'm not sure what the odds are you'll have a guide problem, but I am certain it would cost anywhere from $4-8k to fix if your timing chain jumps or breaks because of a guide failure. Broken guides do not give any warning.

[PalmerWMD]

in most cases there isn't a noise though - just the sound of valves and piston heads hitting each other for a split second before the engine is toast.

It's an ugly crunching noise...

Fred....

[Q451990]

You would know... heard it twice?

Mine just slipped a couple of teeth I guess... it still ran, just shook like heck and backfired through the exhaust a lot. I shut it down quick, but not fast enough. Pulled it in to a parking lot, opened hood, listened, then pulled in to parking space... should have turned it off in the road. In any case it felt like 4 dead injectors at once - thought maybe something came unpluged since I'd always heard the car would just cut off... Guess I was lucky!

Heath