is the 3.5L 6 cyl 1994 LHS an interference engine?

Hi

Does anyone know if the engine in a 1994 LHS is an interference engine (aka
crash motor)? It's a 3.5L 6 cyl.

Thanks

 

The 3.5 is not an interference engine.

 

According to the Gates Timing Belt Replacement Guide
(http://www.gates.com/brochure.cfm?brochure=2256&location_id=3487 -
click the pdf link - give it time to download even if it acts like it's
done), it *is* an interference engine.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

It is an interference engine, that's why if you ever set up the timing marks
at top dead center with the heads off you will see that the piston is not
really at TDC. The reason behind that is because if the cam rotates while
installing the belt the valve could slam into the piston and cause damage.
The marks were offset to prevent this.

 

--

It is an interference engine, that's why if you ever set up the timing marks
at top dead center with the heads off you will see that the piston is not
really at TDC. The reason behind that is because if the cam rotates while
installing the belt the valve could slam into the piston and cause damage.
The marks were offset to prevent this.

 

It's not. Just let folks that have broken their belts answer and that way
there's no confusion.

 

Is that true specifically of 94's? I may have read discussions on this
in the past in which it was concluded (at least by some) that certain
years were iterference, others were not (even though the Gates guide
shows them all as interfeence).

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

The Gates book has its share of errors.
(in this case, errors sell timing belts)

I've replaced scores of these belts and not a one ever bent a
valve. That is more than a coincidence.

My Mitchell On Demand lists the 3.5 as a non-interference engine,
it also lists the 3.2 as an interference engine. The Mitchell
text is direct from ChryCo.

The engine has been out what, 13 years now, yet I have yet to see
anyone post a complaint of a 3.5 with bent valves in -any-
appropriate newsgroup, plenty of incidences posted for other
engines that -are- interference though.

 

Thanks for all of the replies. I'm in the process of taking a cautious
approach. I'm going to replace the timing belt. I'm going to leave off
the harmonic balancer and the accessory belts. Then I'm going to start
the engine. If it seems to run ok, then I will replace the water pump and
finish the job.

Random

 

Apparently DC is schizophrenic on the point. You say Mitchell quotes
Chryco as saying the 3.5 is non-interference. If that is correct (and
applies to all years/versions), FWIW (apparently not much) my '99 LH-car
FSM (on page 9-71 - 3.2/3.5 Engine Components - and page 9-100 - 'Timing
Belt Removal') has bold text warnings: "NOTE The 3.2/3.5 are a NON
[their emphasis] free-wheeling design" and "Caution: The 3.2/3.5L are
NOT [their emphasis] freewheeling engines. Therefore care should be
taken not to rotate the camshafts or crankshaft with the timing belt
removed" respectively.

As an added piece of confusion, there are several threads on the 300M
Club forums where this question is discussed. Here's one of them:
http://300mclub.org/forums/viewtopic.php?t=3906&postdays=0&postorder=asc&start=0

ja300mes is a DC dealer tech and Red Baron is an ASE certified master
mechanic and fleet manager and holds the 1/4 mile track record for
normally aspirated 300M's - they both say it's interference (at least
for 2nd gen cars). I'm not disagreeing with you - I've just seen
convincing claims on both sides. I'm still wondering if there are maybe
some year-to-year differences that may be causing at least some of the
contradictory claims by apparently equally qualified people.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Dunno Bill.

The FSM lumps the 3.2 and 3.5 service information together,
perhaps they felt that a blanket statement about the engines
being interference would be easier for their mechanics to digest
than if they only called out the one that actually is.

My Gates guide lists all 3.5s as non-interference and I have yet
to see or hear of a crashed 3.5 due to a timing belt mishap, and
I have had them towed in with the belt wrapped around the
crankshaft pulley, they ran fine after repair.
Brother in-law works at the local Dodge dealership part dept, he
has never seen a 3.5 need the heads pulled because of a broken
timing belt.

It's also possible that the OEM belt supplier and myself are
wrong...

 

Oh boy - more contradictions from one source. The on-line Gates T-belt
manual
(http://www.gates.com/downloads/download_common.cfm?file=TBR05.pdf&folder=brochure)
shows all 3.5's as interference.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Fun isn't it?

Gleaning accurate service information (even from the OEMs) is a
-big- issue in the industry.

 

When I owned my 94' LHS I bought the factory service manual. I also know a
tech who works for Chrysler and is factory trained. They both said that the
94' 3.5 engine was NON-INTERFERENCE. Yep, NON. They changed to a
interference engine in the next generation of 3.5 engine design. I read
that as a press release on Chryslers main page when the 300M was released.
That engine had 250hp (in HO trim). The original 3.5 was 215hp.

Steve M.....

 

Gates is wrong (actually, they're wrong an alarming amount of the time).
The first-gen 3.5 is very definitely a free-wheeling engine.

 

WRONG!!

This is not a second-generation (aluminum block) 3.5

It is an IRON BLOCK first-gen 3.5- no interference.

 

Only the aluminum-block 2nd-gen engine is *possibly* interference (and
I'm not SURE that it is). The first-gen iron-block engine (1993-1997) is
DEFINITELY NOT an interference engine.

 

i have seen 2 that have bent valves in the last 10 years when a belt let
loose on the 3.5's
ask anyone who owns a hunydi what they are finding out when the timing belts
let loose at 60 k and the bent valves are not covered under the 100k
powertrain warranty since the belt is scheduled maintenance and the dealers
say prove it