Jeep Garage  - Jeep Forum

Jeep Garage - Jeep Forum (
-   Troubleshooting/Problems (
-   -   Thought I would get more help jeepgarage (

lokiminter 12-22-2010 10:21 AM

Thought I would get more help jeepgarage
well I posted a thread about needing some help from the viewers and only one person responded (thanks Frango100) so I will try this again.

ok, I have a 99 grand cherokee limited with 4.7 V8. I had to replace the radiator 4 times in the last 2 years. I chalk it up to just buying a cheap radiator. I have checked for all the usual head gasket problems.... no green residue on the plugs (pulled all 8), no milky oil, no steam out tail pipe, no bubbles or excess pressure into the overflow tank, no oil residue in cooling system.... it has 200k miles but was running perfectly! until..... I drove it out to my parents shop to replace the radiator again 2 weeks ago. the temp guage never pegged out but it would go up about 3/4 and then come back down, go up and come back down. the last mile or so it went up to 3/4 and stayed so i got down the driveway real fast and shut it off. after about 5 min of BSing with dad, i started it to pull it in the the garage..... it would barely start and when it did, it was running horrible, then i heard one little knock and shut it down immediately and pushed it in the garage. 4 hours later, once the radiator was replaced, upon restart, it was missing on one maybe two cylinders and knocking like crazy. but the knock is coming from the top end, like a rocker or the valve getting hit by the piston? my dad has been working on cars for 35 years and it is puzzling him why getting it hot has caused a knock in the top end.
with all that said, we are rebuilding. but i want more HP than the stock 235. I have never "built" an engine and my dad is a ford nut so neither of us has much knowledge of my 4.7 "semi-hemi". i need to be pointed in the right direction as far as aftermarket performance. I would like to put an aggressive cam in it, along with headers, and perhaps a cold air intake. And i have seen in other forums that some parts from later model 4.7's (circa 2008) are interchangable with my 99' 4.7 for more power (such as the intake plenum). not real sure though. I would like to have 300-350HP when i get done. I just think a 5000 pound SUV with AWD is a perfect sleeper to suprise an unsuspecting mustang, camaro, tuner import. lol. I know I have put alot in this answer column but I wanted to make sure you had the whole picture. thanks for your help

NeilF 12-22-2010 11:05 AM

Re: Thought I would get more help jeepgarage

I'm no expert as I'm new to the Jeeps too, got mine last thursday which is a 4.7ho.

I'm not new to tuning though and have built a lot of engines, mainly forced induction stuff but also a few nasps kicking out over 100bhp per litre.

So far I've only found for forged pistons, rods, etc. but it isn't really difficult to get bits made to your spec, just contact a few manufacturers directly and also look at engines with similar bores, strokes, etc. for parts that you can adapt to use.

It sounds to me from your description that you've pressurised the cooling system to blow rads so often rather than just having crap aftermarket luck, I'd put money on blown head gasket and likely warped head.

I haven't seen any headers available and as I'm in the UK anyway it looks like my best option will be to get some flanges waterjetted and piece together a pair from there as I think there are big gains to be had along with a decent system.

Induction on my 2002 HO doesn't at first look appear to be too bad, so I'm not convinced on massive gains from an induction kit.

There's probably a bit to be gained with a remap and decent headers and free flow exhaust so I think that'll be my first choice to develop.



woosch 12-22-2010 11:25 AM

Re: Thought I would get more help jeepgarage
I'm wondering why you think it's a rad problem? What you describe sounds more like a bad water pump or thermostat.

Our Durango showed similar hot/cool issues and proved to be a faulty water pump. Thankfully I caught it before it really pegged the temp and damaged the head gasket.

As for rebuilding, I agree with Neil, check around with a few manufacturers for compatible parts.

08Hemi 12-22-2010 11:30 AM

Re: Thought I would get more help jeepgarage
talk to Scottina06...he has done A LOT to his 4.7 (low 13's in the 1/4 IIRC)

robpp 12-22-2010 11:39 AM

Re: Thought I would get more help jeepgarage
all of that..............and the question I get is you 'want to know about all sorts of high performance parts for your 4.7'/

1. i would talk to nick at air ram.
2. talk to scottina06; he knows quite a bit about the 4.7.
2. the dodge boys do a lot more to the 4.7 than the jeepers of today....they just get the hemi. i would google and prepare to do some reading. this is the internet; be sure to qualify anything you read or are told. thats your DUE DILLIGENCE to yourself.

and I cant resist so one point about the sarcasm in your title and such: I think what you saw was that this forum doesnt have a huge high perf 4.7 presence. and with that, peeps will not just whore up a thread with halffast answers and such (most of the time) :lol: ME: I'd rather not get an answer than get one that provides ZERO information......sort of like this one :D

lokiminter 12-22-2010 04:14 PM

Re: Thought I would get more help jeepgarage
ok, to woosh- thanks for the reply, the temp going up and down was because I was running out of coolant as I drove to my parents garage. and the radiators have all developed leaks in different places ( first one blew the whole side out, second time got a pin hole right in the center of the radiator, third blew the seal at the caps, fourth leaked where one of the flues was soldered at the cap, and the last one just had a crack in one of the flues.) The radiator cap and thermostat was replaced with every radiator. In my mind, with 200k miles and 11 years of on and off road abuse, if i have that much pressure building in my cooling system, it is going to "pop" the cap and blow off into the overflow jug, or it is going to blow a hose or clamp or it is going to do something else than blow a radiator 5 times. I mean, we pressure test cooling systems starting at 30psi. so shouldn't a hose or the cap or something else leak rather than 5 new radiators? but i have taken note of your suggestion and will replace the water pump during the rebuild.

to robpp- thanks as well for your reply. I get the feeling that my title was a bit sarcastic.... it was not. with the potential i see in this truck, i thought more people would have information on bolt on power adders. apparently, there are not as many people like me. I have done just what you said for the last 2 or 3 weeks. gotten online and read.... and read.... but nothing is concrete. most of the time people with say " well i think others have used this part from this company and it worked with out too many problems..." - I don't want or have time for "without too many problems". I looked to this forum for people who have done mods and can say "I did this mod from this company, part #, and it worked great". I don't have the resources or experience as probably most of jeepgarage members, so where you thought i was being sarcastic was really just someone looking for a solid answer.

Scottina06 12-22-2010 06:15 PM

Re: Thought I would get more help jeepgarage
OK...I responded to your pm.

Like one responded above...check out and have a talk with Nick. BUT...if you have the cash or a company willing to work witrh you.....the 4.7 can be made a beast. I HAD the same 4.7 as you and I added the 4.7 HO cams, 08 intake manifiold and airram adapters, fastman ported tb, 180 tstat, K&N intake and a custom tune using an SCT.....BUT I wanted more. So I worked with a local race engine builder, found a low mile 08 4.7, had it bored to 3.85, stroked to 3.75 and sleeved to about 5.7L. It also has custom cams, pistons, rods, bolts, forged crank, billet TB etc etc. Comp cams will custom mill you any cams you want, K1 tech will build you any pistons, crank etc that you want.

I recommend you stay with the above gen 1 mods that i did and go for a custom cam and pistons...then you have to get an SCT tune and superchips tranny tune. Hope that helps....

oh...and my truck is a low 13 second on 87 gas......
Im still working on a custom intake mani using a mustang 4.6 manifold and the airram adapters. Im also looking into forced induction...which I can do even on my stokked gen 2 4.7 becasue of the deck height of the gen 2

All times are GMT -5. The time now is 08:56 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community