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Is the 3.5L an interference engine?

46K views 45 replies 27 participants last post by  00RT 
#1 ·
I have a '95 Vision Tsi with the 3.5L V6. I am noticing a few drops of coolant perhaps from the water pump. I think this may cause the timing belt to slip?

If so, can the engine lunch itself by having the valves meet the piston at an awkward moment? (interference engine)

Or, will it just quit working with no engine damage?

If so, I probably should fix it soon, otherwise, I'll wait until the leak becomes bigger.
 
#2 ·
I have read that the 1st gen 3.5 is a freewheel design and the 2nd gen 3.5 is an interference engine.
 
#4 ·
Yep, that is why I didn't rush to put a timing belt into my car. I have turned 128K+ on the original belt. Something tells me its life is about up. I am actually waiting until I can afford the timing belt, tensioner, water pump, serpentine belt all at one time. :(
 
#5 ·
the 3.2 and both 3.5s are non-interference. the 2.7 and 3.3 (i THINK) are interference, which is why they have timing chains and not belts. i'm not positive either way, but it seems logical.
 
#7 ·
viprman said:
I am actually waiting until I can afford the timing belt, tensioner, water pump, serpentine belt all at one time. :(
The timing belt is ~$50. I also have a '97. I didn't change the water pump or tensioner pulley. The water pump is the better design (6-bolt) and the tensioner was metal (earlier are plastic?). Neither were too cheap. I think the WPump was $80. :eek:

You can wait on the serpentine belt it's so easy to change.
 
#8 ·
Yep, the 3.5 is freewheeling...as I found out at 93K mi., on I-25, at 80 mph. Threw me for a while, as it cranked, but sounded just a bit 'funny'. It's an 'easy' replacement, but can take a while. I did mine in the rest area, as I didn't want to shell out for a 200 mile tow, home. Took me about 6 hours, but that was a lot of running-around time, too.

BEWARE!!! Because you have a '95, you MIGHT have a '94's timing belt, at least according to some parts stores. The '95 belt I bought was too long by a couple of teeth, resulting in -0- tension when I pulled the 'pin' on the tensioner thingy. Fortunately, the shop had a '94's belt, and stayed open 'till I could exchange 'em (I asked if they had different part numbers, in a stroke of logic, they did, and sure enough...). Also beware of WP leaks as *I* think the water pump leaking on ours accelerated my belts death, as it expired early. It had leaked for months, though, albeit slowly, and I'd just put it all off until 100K...sure enough, it bit me. Least we weren't in West Texas when it happened....

Happy wrenching!

Kelly B
'95 ES, 3.5L, OEM tranny a@ 107K, soon to have a non-leaking high pressure PS hose *and* PIAA 959's where the OEM 'fogs' are.... finally, a car you can drive at night!
K&N filter, no intake restrictor, down to half an air-intake box...
 
#9 ·
I was flipping thru my manual looking for something else and the timing belt section caught my eye. Certainly the 3.5l was a chain ??? No, of course its not. I've got 127,000 miles on mine and its original. Doh !

I read up in the manual and figured I would have a go at it last weekend. I spent the better part of the weekend trying to get the damn crankshaft damper off the crank. So close, but yet so far !!! I could not get it to budge. I called Chrysler this morning and the guy tells me $382.50 to change the timing belt. Daaamammn. I may have another go at it. I did get in there enough to see that the belt looked to still be in very good condition. I put two new hoses on it, cleaned my radiator and changed out the transcooler line.

What kind of puller have yall used to pull the harmonic balancer on the 3.5L engine ?? It looks like I can buy a specialized one from Matco for $110. Still a lot cheaper than $380.

Also, how hard is it to put back on ?? The Chrysler service guy made it out to be really hard and very likely I would strip out the threads in the crankshaft >??? Sounds like a load of it. Who out there has BTDT ??

Thanks,
RIchard
 
#12 ·
Well The valves in a non are not suppose to hit the heads, but, I have seen it done on ford motors, and one 3.5 first gen. if the revs are up there when it goes, but under normal driving it should not hit, even on the highway you might be at what, 3g's maybe, and in a non it whould have to break just at the right moment for the piston to hit the valve with the revs up to about 6g's. if the heads have ever been milled the greater the chance, and it is a good idea to change the water pump if your changing the belt, if the pump goes and the engine over heats, boom goes the head gaskets, not a cheap fix if you go have it done


97 Sport 148,000 miles and counting
 
#14 ·
Umm... sorry, but it IS NOT an interference engine, just like the good 'ol 3.0 Mitsubishi v-6.

mckellyb said:
Yep, the 3.5 is freewheeling...as I found out at 93K mi., on I-25, at 80 mph. Threw me for a while, as it cranked, but sounded just a bit 'funny'. It's an 'easy' replacement, but can take a while.
It may be a fluke that your's did bend a few valve or do some other damage when the belt broke but they are otherwise non-interference.

The 3.0 v-6 in my sis's old '90 Cutlass Callais was an interference motor as it bent every single valve in it when the nylon teeth on the timing chain sprocket got a little too warm and the chain slipped.
 
#15 ·
Great to know that I don't have to pull that crank dampner off. I might swing by a pick a part in here in Houston and have a look at some of the 3.5L engines they've got in many states of dissasembly. I' ll have a good look and see how its done. Thanks for the heads up, it'll be a BIG relief.

Richard
 
#16 ·
you'll need to use a bench vise to compress the tensioner and a small allenhead to hold it cause it's the only thing that'll hold to the pressure...normal pins will bend and snap.
and be prepared to cut a little off the allenhead to fit the tensioner in place and throw it away afterwards.
 
#18 ·
Here's an exerpt from my factory service CD-R:

CAMSHAFT TIMING BELT - 3.5L DOHC
Replace timing belt every 105,000 miles or after 84 months,
whichever occurs first.
CAUTION: Failure to replace a faulty camshaft timing belt may result
in serious engine damage.
The condition of camshaft drive belts should always be
checked on vehicles which have more than 50,000 miles. Although some
manufacturers do not recommend belt replacement at a specified
mileage, others require it at 60,000-100,000 miles. A camshaft drive
belt failure may cause extensive damage to internal engine components
on most engines, although some designs do not allow piston-to-valve
contact. These designs are often called "Free Wheeling".
Many manufacturers changed their maintenance and warranty
schedules in the mid-1980’s to reflect timing belt inspection and/or
replacement at 50,000-60,000 miles. Most service interval schedules in
this manual reflect these changes.
Belts or components should be inspected and replaced if any
of the following conditions exist:
* Cracks Or Tears In Belt Surface
* Missing, Damaged, Cracked Or Rounded Teeth
* Oil Contamination
* Damaged Or Faulty Tensioners
* Incorrect Tension Adjustment
 
#20 ·
The must have showed you stuff from another car.

My waterpump seized, and at first slowing down the timing belt and eventually causing it to snap. This went on for a good 10 min while I found a spot to pull over. I had the engine at 4,000 rpms when it did go.

I had the car towed to the dealer, they changed the waterpump, tensioner and belt and I was on my way.

Also, from Motor Trend's In-depth Guide to the 1993 Intrepid it specifically states the engine is non-interference (3.5L).
 
#22 ·
IntrepidLHS said:
Here's an exerpt from my factory service CD-R:

CAMSHAFT TIMING BELT - 3.5L DOHC
Replace timing belt every 105,000 miles or after 84 months,
whichever occurs first.
CAUTION: Failure to replace a faulty camshaft timing belt may result
in serious engine damage.
Read what you just said -

3.5L DOHC. Our 1st gen 3.5's are SOHC - one cam driving 12 valves on each side. Perhaps (and i know nothing about 2g's, so this could be wrong) but it might be for the second gen 3.5's, or the 300M 3.5, or the Prowler 3.5 (I don't know what the difference, if any, between these three engines is).
 
#23 ·
About a year ago, I was pulling out in to fast moving traffic and on the first to second up shift, bam their went my timing belt, the car had 128,000 on her. The valves were toast only because of the high RPM’s according to Dodge.:mg:
 
#24 ·
atlanta35 said:
About a year ago, I was pulling out in to fast moving traffic and on the first to second up shift, bam their went my timing belt, the car had 128,000 on her. The valves were toast only because of the high RPM’s according to Dodge.:mg:
or they ripped you off....

I still can't imagine a non-interference engine self destructing when the timing belt goes.

I'll have to see it to believe it.
 
#26 ·
Black94ES said:
or they ripped you off....

I still can't imagine a non-interference engine self destructing when the timing belt goes.

I'll have to see it to believe it.
No, Dodge didn't rip me off, A friend and I did all the repair our selfs. I called dodge to ask how this happened on a non-interference engine. I saw it with my own eyes and repaired it with my own hands, those valves were toast.
 
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